diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..1edcd0d --- /dev/null +++ b/LICENSE @@ -0,0 +1,29 @@ +BSD 3-Clause License + +Copyright (c) 2017, Nishant Kumar +All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + +* Redistributions of source code must retain the above copyright notice, this + list of conditions and the following disclaimer. + +* Redistributions in binary form must reproduce the above copyright notice, + this list of conditions and the following disclaimer in the documentation + and/or other materials provided with the distribution. + +* Neither the name of the copyright holder nor the names of its + contributors may be used to endorse or promote products derived from + this software without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE +FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR +SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/Nishant_resume.js b/Nishant_resume.js deleted file mode 100644 index 50d65cc..0000000 --- a/Nishant_resume.js +++ /dev/null @@ -1,117 +0,0 @@ -/** - * The Curriculum vitae of Nishant Kumar - * - * Hi there, I am Nishant. I am UI Engineering Lead, JavaScript Engineer, - * Mozila Tech Contributor, CodeMentor Front-end Expert, Writer from India. - */ - -(function() { - 'use strict'; - - /* - About Me - */ - var me = { - name: 'Nishant Kumar', - job: 'UI Engineering Lead', - organization: 'Big Parser', - status: 'Not availble for Hire full time', - location: 'India', - experience: '5 years', - skills: { - 'scripting-language' :['javascript'] - 'frameworks': ['angular.js','backbone.js','sails.js'], - 'library' : ['jQuery'] - 'tools': ['Gulp', 'Grunt', 'bower','yoman','Git'], - 'testing': ['jasmine', 'protractor'], - 'backend': ['node.js', 'express.js'], - 'dataBase': ['mongoDb', 'SQL'], - 'uncategorized' : ['C','C#','HTML','CSS', 'HTML5','JSON'] - } - }; - - /* - Contact Details - */ - var me_contact = { - 'email' : 'nihantanu@gmail.com', - 'skypeId' : 'mfsi_nishantk', - 'linkedIn' :'http://in.linkedin.com/in/nishantkumar1' - 'gitHub' : 'github.com/nishant8BITS' - 'stackOverFlow' : 'http://stackoverflow.com/users/430803/nishant' - 'codementor': 'codementor.io/nihantanu' - } - - /* - Education - */ - var education = { - 'post-Graduate': { - 'college': 'Birla Institute of Technology and Science, Pilani', - 'Major' : 'Software System', - 'Year' :'2016' - }, - 'graduation' : { - 'college': 'ICFAI University, Dehradun', - 'Major' : 'Computer Science & Engineering', - 'Year' :'2011' - } - } - - /** - * Nice things people have said about me. - */ - - /** - * Nishant is a very smart and thoughtful person as an engineer. He truly cares - * about helping others and values the learning experience for young software - * engineers. He is very patient - a key trait as an engineer. Nishant will help - * guide you through problems and help you understand software engineering - * concepts. Hands down I would hire Nishant to be on a team that will not only - * help a business but help other engineers grow as well. - * -Gary Tsai, Software Engineer - */ - - /** - * Nishant is a quick learner and he has very deep understanding on UI stack. He - * also is a good mentor and help other to understand the technology stack. One - * good thing I observed while working with him is he always focus on insist on - * highest standard in his code/solution as well as idea. Keep it up. - * -Apurv Gupta (WDE II at Amazon) - */ - - /** - * Nishant is one of the best person I'm working with. Along with his strong - * technical understanding of how things work, he also keeps on motivating to team - * and helps them to participate effectively & maintaining their productivity to - * better work towards achieving a goal. He always prefers to have full stack - * knowledge of the product & leads a team with great enthusiasm. He can deliver - * end to end any product he is working on. - * -Yash Shah (SRE at Linkedin) - */ - - /** - * I have been working with Nishant since last one year on a cloud-based product, - * He is one of the vibrant contributor in the team and always been dedicated to - * his work. He has very good level of knowledge when it comes to overall front-end - * architecture solutions and specifically on frameworks like backbone & angular. - * -Mohiuddin Parekh ( Founder & CEO at Decojent) - */ - - /** - * I first met Nishant 3 months ago when I told him I was looking for help with - * AngularJS and asked him to mentor me. One of the first things I noticed was that - * he had a great learning attitude, because he told me that he was looking forward - * to learning from me, something I wasn’t expecting from a mentor! He is fun, - * sweet, generous and has a great sense of humor. We have quickly become friends - * and I think we have spent more time hanging out on Telegram (instant messaging) - * and Skype than we have coding. I had never written my own AngularJS directive - * before so I asked him if he could write one for me for an autocomplete feature. - * I was impressed with his work and because of it I was then able to write my own - * directives. We have spent a lot of time chatting and I think there is so much - * more he can do that I have not yet seen. I can see he also has a passion for - * startups. - * -Jenny Swift (Software Engineer) - */ - -})(); diff --git a/README.md b/README.md index fd68472..520e425 100644 --- a/README.md +++ b/README.md @@ -1,11 +1,18 @@ ![](coverPage.png) -## This Book will be completed by June 1 2016 and available to buy. If you want me to sent early copy of this book then please add your name and email address in google form here [Google Form](http://goo.gl/forms/QSpxVtvsNb). + [![Join the chat at https://gitter.im/nishant8BITS/123-Essential-JavaScript-Interview-Question](https://badges.gitter.im/nishant8BITS/123-Essential-JavaScript-Interview-Question.svg)](https://gitter.im/nishant8BITS/123-Essential-JavaScript-Interview-Question?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) +##License + +This book is released under a Creative Commons Attribution-Noncommercial- No Derivative Works 3.0 United States License. + +What this means it that the project is free to read and use, but the license does not permit commercial use of the material (i.e you can freely print out the questions for your own use, but you can't sell it). I'm trying to best to publish all of my books in a free + purchased (if you would like to support these projects) form so I would greatly appreciate it if you would respect these terms. + +Copyright Iurii Katkov and Nishant Kumar, 2017. + ## Have question for me ? -[Ask me @nishant kumar](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) # 123-JavaScript-Interview-Question ## 1. Difference between `undefined` and `not defined` in JavaScript @@ -39,7 +46,6 @@ console.log(y); // Output: ReferenceError: y is not defined [http://stackoverflow.com/questions/20822022/javascript-variable-definition-declaration](http://stackoverflow.com/questions/20822022/javascript-variable-definition-declaration) ## Have doubt in this question ?? -[Schedule time to discuss with me @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) ## 2. What will be the output of the following code? @@ -74,7 +80,6 @@ console.log(k); // output 1function ``` ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) ## 3. What is the drawback of creating true private in JavaScript? > One of the drawback of creating a true private method in JavaScript is that they are very memory inefficient because a new copy of the method would be created for each instance. @@ -86,13 +91,13 @@ var Employee = function (name, company, salary) { this.salary = salary || 5000; //Public attribute default value is null // Private method - var increaseSlary = function () { + var increaseSalary = function () { this.salary = this.salary + 1000; }; // Public method this.dispalyIncreasedSalary = function() { - increaseSlary(); + increaseSalary(); console.log(this.salary); }; }; @@ -110,7 +115,6 @@ Here each instance variable `emp1`, `emp2`, `emp3` has own copy of increaseSalar So as recommendation don't go for a private method unless it's necessary. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) ## 4.What is “closure” in javascript? Provide an example? > A closure is a function defined inside another function (called parent function) and has access to the variable which is declared and defined in parent function scope. @@ -137,8 +141,10 @@ var globalVar = "abc"; "innerArg = " + innerArg + "\n" + "innerFuncVar = " + innerFuncVar + "\n" + "globalVar = " + globalVar); - } // end of scope innerFunction)(5); // Pass 5 as parameter -} // end of scope outerFunction )(7); // Pass 7 as parameter + // end of scope innerFunction + })(5); // Pass 5 as parameter +// end of scope outerFunction +})(7); // Pass 7 as parameter ``` `innerFunction` is closure which is defined inside `outerFunction` and has access to all variable which is declared and defined in outerFunction scope. In addition to this function defined inside function as closure has access to variable which is declared in `global namespace`. @@ -154,7 +160,6 @@ globalVar = abc ``` ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) ## 5. Write a mul function which will properly when invoked as below syntax. @@ -255,7 +260,6 @@ while(arrayList.length) { Above implementation can also empty the array. But not recommended to use often. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) ### 7. How to check if an object is an array or not? > The best way to find whether an object is instance of a particular class or not using `toString` method from `Object.prototype` @@ -319,7 +323,6 @@ Array.isArray(arrayList); `Array.isArray` is supported by Chrome 5, Firefox 4.0, IE 9, Opera 10.5 and Safari 5 ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 8. What will be the output of the following code? @@ -335,7 +338,6 @@ console.log(output); > Above code will output `0` as output. `delete` operator is used to delete a property from an object. Here `x` is not an object it's **local variable**. `delete` operator doesn't affect local variable. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 9. What will be the output of the following code? @@ -352,7 +354,6 @@ console.log(output); > Above code will output `1` as output. `delete` operator is used to delete property from object. Here `x` is not an object it's **global variable** of type `number`. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 10. What will be the output of the following code? @@ -369,7 +370,6 @@ console.log(output); > Above code will output `undefined` as output. `delete` operator is used to delete a property from an object. Here `x` is an object which has foo as a property and from self-invoking function we are deleting foo property of object `x` and after deletion we are trying to reference deleted property `foo` which result `undefined`. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 11. What will be the output of the following code? @@ -387,7 +387,6 @@ console.log(emp1.company); `emp1` object doesn't have **company** as its own property. you can test it `console.log(emp1.hasOwnProperty('company')); //output : false` However, we can delete company property directly from `Employee` object using `delete Employee.company` or we can also delete from `emp1` object using `__proto__` property `delete emp1.__proto__.company`. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 12. What is `undefined x 1` in JavaScript @@ -401,7 +400,6 @@ when you run above code and do `console.log(trees);` in chrome developer console **Note:** Please remember you need not check for uninitialized index of array in `trees[3] === 'undefined × 1'` it will give an error, Because `'undefined × 1'` this is just way of displaying uninitialized index of array in chrome. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 13. What will be the output of the following code? @@ -416,7 +414,6 @@ console.log(trees.length); So when delete operator removes an array element that deleted element is not longer present in array. In place of value at deleted index `undefined x 1` in **chrome** and `undefined` is placed at the index. If you do `console.log(trees)` output `["xyz", "xxxx", "test", undefined × 1, "apple"]` in Chrome and in Firefox `["xyz", "xxxx", "test", undefined, "apple"]`. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 14. What will be the output of the following code? @@ -436,7 +433,6 @@ console.log(bar + false); - String + String -> Concatenation ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 15. What will be the output of the following code? @@ -448,7 +444,6 @@ console.log(y); > Above code will output `undefined` as output. According to `associativity` rule operator with the same precedence are processed based on their associativity property of operator. Here associativity of the assignment operator is `Right to Left` so first `typeof y` will evaluate first which is `undefined` and assigned to `z` and then `y` would be assigned the value of z and then `z` would be assign value `1`. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) #### 16. What will be the output of the following code? @@ -489,7 +484,7 @@ var foo = function bar() { ``` ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) + #### 17. What is the difference between declaring a function in below format? @@ -778,7 +773,7 @@ Unlike function calls and method calls, a constructor call `new Employee('John D The primary role of the constructor function is to initialize the object. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) + ## Question 23 @@ -827,7 +822,7 @@ In Javascript function defined inside has access to outer function variable and - Function can be returned from function ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) + ## Question 25 @@ -882,7 +877,7 @@ methodObject.display(); Here methodObject is an object and display is a method which is associated with methodObject. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) + ## Question 26 @@ -918,7 +913,7 @@ function testCallBack(callback) { testCallBack(display); // Here display function is being passed as callback ``` ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) + ## Question 27 ### Describe Singleton Pattern In JavaScript? @@ -1023,7 +1018,7 @@ console.log(MyNamespace.Singleton.getInstance().publicMethod()); The singleton implemented above is easy to understand. The singleton class maintains a static reference to the lone singleton instance and return that reference from the static getInstance() method. ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) + ## Question 28 @@ -1649,6 +1644,319 @@ delete employee.name; // fails silently unless it's in strict mode ``` +## Question 44 +##### Write a log function which will add prefix `(your message)` to every message you log using console.log ? +> For example, If you log `console.log("Some message")` then output should be **(your message) Some message** + +Logging error message or some informative message is always required when you dealing with client side JavaScript using console.log method. Some time you want to add some prefix to identify message generated log from your application hence you would like to prefix your app name in every console.log. + +A general way to do this keep adding your app name in every console.log message like + +```javascript +console.log('your app name' + 'some error message'); +``` +But doing in this way you have to write your app name everytime when you log message using console. + +There are some best way we can achieve this + +```javascript +function appLog() { + var args = Array.prototype.slice.call(argument); + args.unshift('your app name'); + console.log.apply(console, args); +} + +console.log(appLog("Some error message")); +//output of above console: 'your app name Some error message' +``` + +## Question 45 +##### Write a function which will test string as a literal and as an object ? + +For example: We can create string using string literal and using String constructor function. + +```javascript + // using string literal + var ltrlStr = "Hi I am string literal"; + // using String constructor function + var objStr = new String("Hi I am string object"); +``` +> We can use typeof operator to test string literal and instanceof operator to test String object. + +```javascript + function isString(str) { + return typeof(str) == 'string' || str instanceof String; + } + + var ltrlStr = "Hi I am string literal"; + var objStr = new String("Hi I am string object"); + console.log(isString(ltrlStr)); // true + console.log(isString(objStr)); // true +``` +## Question 46 +##### What is typical use case for anonymous function in JavaScript ? + +> Anonymous functions basically used in following scenario. + +1. No name is needed if function is only used in one place, then there is no need to add a name to function. + + Let's take the example of setTimeout function + + ```javascript + setTimeout(function(){ + alert("Hello"); + },1000); + ``` + Here there is no need of using named function when we are sure that function which will alert `hello` would use only once in application. + +2. Anonymous functions are declared inline and inline functions have advantages in the case that they can access variable in the parent scopes. + + Let's take a example of event handler. Notify event of particular type (such as click) for a given object. + + Let say we have HTML element (button) on which we want to add click event and when user do click on button we would like to execute some logic. + + ```html + + ``` + Add Event Listener + + ```javascript + var btn = document.getElementById('myBtn'); + btn.addEventListener('click', function () { + alert('button clicked'); + }); + ``` + + Above example shows used of anonymous function as a callback function in event handler. + +3. Passing anonymous function as a parameter to calling function. + + Example: + + ```javascript + // Function which will execute callback function + function processCallback(callback){ + if(typeof callback === 'function'){ + callback(); + } + } + + // Call function and pass anonymous function as callback + processCallback(function(){ + alert("Hi I am anonymous callback function"); + }); + ``` +The best way to take decision for using anonymous function is to asked. + +> Will the function which I am going to define will use anywhere else. + +If your answer is yes then go and create named function rather anonymous function. + +**Advantage of using anonymous function:** + +1. It can reduce a bit of code, particularly in recursive function and in callback function. +2. Avoid needless global namespace pollutions. + +## Question 47 +##### How to set a default parameter value ? + +> If you are coming from python/c# you might be using default value for function parameter incase value(formal parameter) has not been passed. For Instance : + +```python +// Define sentEmail function +// configuration : Configuration object +// provider : Email Service provider, Default would be gmail +def sentEmail(configuration, provider = 'Gmail'): + # Your code logic +``` +**In Pre ES6/ES2015** + +There are a lot of ways by which you can achieve this in pre ES2015. + +Let's understand below code by which we achieved setting default parameter value. + +**Method 1: Setting default parameter value** + +```javascript +function sentEmail(configuration, provider) { + // Set default value if user has not passed value for provider + provider = typeof provider !== 'undefined' ? provider : 'Gmail' + // Your code logic +; +} +// In this call we are not passing provider parameter value +sentEmail({ + from: 'xyz@gmail.com', + subject: 'Test Email' +}); +// Here we are passing Yahoo Mail as a provider value +sentEmail({ + from: 'xyz@gmail.com', + subject: 'Test Email' +}, 'Yahoo Mail'); +``` + +**Method 2: Setting default parameter value** + +```javascript +function sentEmail(configuration, provider) { + // Set default value if user has not passed value for provider + provider = provider || 'Gmail' + // Your code logic +; +} +// In this call we are not passing provider parameter value +sentEmail({ + from: 'xyz@gmail.com', + subject: 'Test Email' +}); +// Here we are passing Yahoo Mail as a provider value +sentEmail({ + from: 'xyz@gmail.com', + subject: 'Test Email' +}, 'Yahoo Mail'); +``` + +## Question 48 +##### Write code for merge two JavaScript Object dynamically. +> Let say you have two object + +```javascript +var person = { + name : 'John', + age : 24 +} + +var location = { + addressLine1 : 'Some Location x', + addressLine2 : 'Some Location y', + city : 'NewYork' +} +``` +Write merge function which will take two object and add all the own property of second object into first object. + +```javascript +merge(person , location); + +/* Now person should have 5 properties +name , age , addressLine1 , addressLine2 , city */ +``` +**Method 1: Using ES6, Object assign method** + +```javascript +function merge(toObj,fromObj){ + return Object.assign(person,location); +} +``` + +**Method 2: Without using in-built function** + +```javascript +function merge(toObj, fromObj) { + // Make sure both of the parameter is an object + if (typeof toObj === 'object' && typeof fromObj === 'object') { + for (var pro in fromObj) { + // Assign only own properties not inherited properties + if (fromObj.hasOwnProperty(pro)) { + // Assign property and value + toObj[pro] = fromObj[pro]; + } + } + }else{ + throw "Merge function can apply only on object"; + } +} +``` +## Question 49 +##### What is non-enumerable property in JavaScript and how can create ? + +>Object can have properties that don't show up when you iterate through object using for...in loop or using Object.keys() to get an array of property names. This properties is know as non-enumerable properties. + +Let say we have following object + +```javascript +var person = { + name: 'John' +}; +person.salary = '10000$'; +person['country'] = 'USA'; + +console.log(Object.keys(person)); // ['name', 'salary', 'country'] +``` +As we know that person object properties `name`, `salary` ,`country` are enumerable hence it's shown up when we called Object.keys(person). + +To create a non-enumerable property we have to use **Object.defineProperty()**. This is a special method for creating non-enumerable property in JavaScript. + +```javascript +var person = { + name: 'John' +}; +person.salary = '10000$'; +person['country'] = 'USA'; + +// Create non-enumerable property +Object.defineProperty(person, 'phoneNo',{ + value : '8888888888', + enumerable: false +}) + +Object.keys(person); // ['name', 'salary', 'country'] +``` +In above example `phoneNo` property didn't show up because we made it non-enumerable by setting **enumerable:false** + +Now let's try to change value of `phoneNo` + +```javascript +person.phoneNo = '7777777777'; +``` +Changing non-enumerable property value will return error in `strict mode`. In non-strict mode it won't through any error but it won't change the value of phoneNo. + +**Bonus** + +**Object.defineProperty()** is also let you create read-only properties as we saw above, we are not able to modify phoneNo value of a person object. + +## Question 50 +##### What is Function binding ? + +> Function binding falls in advance JavaScript category and this is very popular technique to use in conjunction with event handler and callback function to preserve code execution context while passing function as a parameter. + +Let's consider the following example: + +```javascript +var clickHandler = { + message: 'click event handler', + handleClick: function(event) { + console.log(this.message); + } +}; + +var btn = document.getElementById('myBtn'); +// Add click event to btn +btn.addEventListener('click', clickHandler.handleClick); +``` + +Here in this example clickHandler object is created which contain message properties and handleClick method. + +We have assigned handleClick method to a DOM button, which will be executed in response of click. When the button is clicked, then handleClick method is being called and console message. Here console.log should log the `click event handler` message but it actually log `undefined`. + +The problem of displaying `undefined` is because of the execution context of clickHandler.handleClick method is not being saved hence `this` pointing to button `btn` object. We can fix this issue using bind method. + +```javascript +var clickHandler = { + message: 'click event handler', + handleClick: function(event) { + console.log(this.message); + } +}; + +var btn = document.getElementById('myBtn'); +// Add click event to btn and bind the clickHandler object +btn.addEventListener('click', clickHandler.handleClick.bind(clickHandler)); +``` + +`bind` method is available to all the function similar to call and apply method which take argument value of `this`. + + #Objective Question ## Hoisting @@ -1693,6 +2001,154 @@ var employeeId = '1234abe'; Answer: 2) undefined +###4. What would be the output of following code? + +```javascript +var employeeId = '1234abe'; +(function() { + console.log(employeeId); + var employeeId = '122345'; + (function() { + var employeeId = 'abc1234'; + }()); +}()); +``` + +1. '122345' +2. undefined +3. '1234abe' +4. ReferenceError: employeeId is not defined + +Answer: 2) undefined + +###5. What would be the output of following code? + +```javascript +(function() { + console.log(typeof displayFunc); + var displayFunc = function(){ + console.log("Hi I am inside displayFunc"); + } +}()); +``` + +1. undefined +2. function +3. 'Hi I am inside displayFunc' +4. ReferenceError: displayFunc is not defined + +Answer: 1) undefined + +###6. What would be the output of following code? + +```javascript +var employeeId = 'abc123'; +function foo(){ + employeeId = '123bcd'; + return; +} +foo(); +console.log(employeeId); +``` + +1. undefined +2. '123bcd' +3. 'abc123' +4. ReferenceError: employeeId is not defined + +Answer: 2) '123bcd' + +###7. What would be the output of following code? + +```javascript +var employeeId = 'abc123'; + +function foo() { + employeeId = '123bcd'; + return; + + function employeeId() {} +} +foo(); +console.log(employeeId); +``` + +1. undefined +2. '123bcd' +3. 'abc123' +4. ReferenceError: employeeId is not defined + +Answer: 3) 'abc123' + +###8. What would be the output of following code? + +```javascript +var employeeId = 'abc123'; + +function foo() { + employeeId(); + return; + + function employeeId() { + console.log(typeof employeeId); + } +} +foo(); +``` + +1. undefined +2. function +3. string +4. ReferenceError: employeeId is not defined + +Answer: 2) 'function' + +###9. What would be the output of following code? + +```javascript +function foo() { + employeeId(); + var product = 'Car'; + return; + + function employeeId() { + console.log(product); + } +} +foo(); +``` + +1. undefined +2. Type Error +3. 'Car' +4. ReferenceError: product is not defined + +Answer: 1) undefined + +###10. What would be the output of following code? + +```javascript +(function foo() { + bar(); + + function bar() { + abc(); + console.log(typeof abc); + } + + function abc() { + console.log(typeof bar); + } +}()); +``` + +1. undefined undefined +2. Type Error +3. function function +4. ReferenceError: bar is not defined + +Answer: 3) function function + ## Object ###1. What would be the output of following code ? @@ -1702,7 +2158,7 @@ Answer: 2) undefined 'use strict'; var person = { - name: 'Nishant' + name: 'John' }; person.salary = '10000$'; person['country'] = 'USA'; @@ -1722,10 +2178,6 @@ Answer: 2) undefined Answer: 3) ["name", "salary", "country", "phoneNo"] -## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) - - ###2. What would be the output of following code ? ```javascript @@ -1733,7 +2185,7 @@ Answer: 3) ["name", "salary", "country", "phoneNo"] 'use strict'; var person = { - name: 'Nishant' + name: 'John' }; person.salary = '10000$'; person['country'] = 'USA'; @@ -1753,10 +2205,6 @@ Answer: 3) ["name", "salary", "country", "phoneNo"] Answer: 4) ["name", "salary", "country"] -## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) - - ###3. What would be the output of following code ? ```javascript @@ -1797,40 +2245,180 @@ Answer: 2) false false Answer: 2) false false -## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) - - -## Array - -###1. What would be the output of following code? +###5. What would be the output of following code ? ```javascript (function() { - var array = new Array('100'); - console.log(array); - console.log(array.length); + var objA = Object.create({ + foo: 'foo' + }); + var objB = Object.create({ + foo: 'foo' + }); + console.log(objA == objB); + console.log(objA === objB); }()); ``` +1. false true +2. false false +3. true false +4. true true + +Answer: 2) false false -1. undefined undefined -2. [undefined × 100] 100 -3. ["100"] 1 -4. ReferenceError: array is not defined - -Answer: 3) ["100"] 1 - -###2. What would be the output of following code? +###6. What would be the output of following code ? ```javascript (function() { - var array1 = []; - var array2 = new Array(100); - var array3 = new Array(['1',2,'3',4,5.6]); - console.log(array1); - console.log(array2); - console.log(array3); - console.log(array3.length); + var objA = Object.create({ + foo: 'foo' + }); + var objB = Object.create(objA); + console.log(objA == objB); + console.log(objA === objB); +}()); +``` +1. false true +2. false false +3. true false +4. true true + +Answer: 2) false false + +###7. What would be the output of following code ? + +```javascript +(function() { + var objA = Object.create({ + foo: 'foo' + }); + var objB = Object.create(objA); + console.log(objA.toString() == objB.toString()); + console.log(objA.toString() === objB.toString()); +}()); +``` +1. false true +2. false false +3. true false +4. true true + +Answer: 4) true true + +###8. What would be the output of following code ? + +```javascript +(function() { + var objA = Object.create({ + foo: 'foo' + }); + var objB = objA; + console.log(objA == objB); + console.log(objA === objB); + console.log(objA.toString() == objB.toString()); + console.log(objA.toString() === objB.toString()); +}()); +``` +1. true true true false +2. true false true true +3. true true true true +4. true true false false + +Answer: 3) true true true true + +###9. What would be the output of following code ? + +```javascript +(function() { + var objA = Object.create({ + foo: 'foo' + }); + var objB = objA; + objB.foo = 'bar'; + console.log(objA.foo); + console.log(objB.foo); +}()); +``` +1. foo bar +2. bar bar +3. foo foo +4. bar foo + +Answer: 2) bar bar + +###10. What would be the output of following code ? + +```javascript +(function() { + var objA = Object.create({ + foo: 'foo' + }); + var objB = objA; + objB.foo = 'bar'; + + delete objA.foo; + console.log(objA.foo); + console.log(objB.foo); +}()); +``` +1. foo bar +2. bar bar +3. foo foo +4. bar foo + +Answer: 3) foo foo + +###11. What would be the output of following code ? + +```javascript +(function() { + var objA = { + foo: 'foo' + }; + var objB = objA; + objB.foo = 'bar'; + + delete objA.foo; + console.log(objA.foo); + console.log(objB.foo); +}()); +``` +1. foo bar +2. undefined undefined +3. foo foo +4. undefined bar + +Answer: 2) undefined undefined + +## Array + +###1. What would be the output of following code? + +```javascript +(function() { + var array = new Array('100'); + console.log(array); + console.log(array.length); +}()); +``` + +1. undefined undefined +2. [undefined × 100] 100 +3. ["100"] 1 +4. ReferenceError: array is not defined + +Answer: 3) ["100"] 1 + +###2. What would be the output of following code? + +```javascript +(function() { + var array1 = []; + var array2 = new Array(100); + var array3 = new Array(['1',2,'3',4,5.6]); + console.log(array1); + console.log(array2); + console.log(array3); + console.log(array3.length); }()); ``` @@ -1841,10 +2429,6 @@ Answer: 3) ["100"] 1 Answer: 1) [] [] [Array[5]] 1 -## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) - - ###3. What would be the output of following code? ```javascript @@ -1863,10 +2447,6 @@ Answer: 1) [] [] [Array[5]] 1 Answer: 1) 11 -## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) - - ###4. What would be the output of following code? ```javascript @@ -1885,6 +2465,200 @@ Answer: 1) 11 Answer: 3) 6 +###5. What would be the output of following code? + +```javascript +(function(){ + var animal = ['cow','horse']; + animal.push('cat'); + animal.unshift('dog','rat','goat'); + console.log(animal); +})(); +``` + +1. [ 'dog', 'rat', 'goat', 'cow', 'horse', 'cat' ] +2. [ 'cow', 'horse', 'cat', 'dog', 'rat', 'goat' ] +3. Type Error +4. undefined + +Answer: 1) [ 'dog', 'rat', 'goat', 'cow', 'horse', 'cat' ] + +###6. What would be the output of following code? + +```javascript +(function(){ + var array = [1,2,3,4,5]; + console.log(array.indexOf(2)); + console.log([{name: 'John'},{name : 'John'}].indexOf({name:'John'})); + console.log([[1],[2],[3],[4]].indexOf([3])); + console.log("abcdefgh".indexOf('e')); +})(); +``` + +1. 1 -1 -1 4 +2. 1 0 -1 4 +3. 1 -1 -1 -1 +4. 1 undefined -1 4 + +Answer: 1) 1 -1 -1 4 + +###7. What would be the output of following code? + +```javascript +(function(){ + var array = [1,2,3,4,5,1,2,3,4,5,6]; + console.log(array.indexOf(2)); + console.log(array.indexOf(2,3)); + console.log(array.indexOf(2,10)); +})(); +``` + +1. 1 -1 -1 +2. 1 6 -1 +3. 1 1 -1 +4. 1 undefined undefined + +Answer: 2) 1 6 -1 + +###8. What would be the output of following code? + +```javascript +(function(){ + var numbers = [2,3,4,8,9,11,13,12,16]; + var even = numbers.filter(function(element, index){ + return element % 2 === 0; + }); + console.log(even); + + var containsDivisibleby3 = numbers.some(function(element, index){ + return element % 3 === 0; + }); + + console.log(containsDivisibleby3); +})(); +``` + +1. [ 2, 4, 8, 12, 16 ] [ 0, 3, 0, 0, 9, 0, 12] +2. [ 2, 4, 8, 12, 16 ] [ 3, 9, 12] +3. [ 2, 4, 8, 12, 16 ] true +4. [ 2, 4, 8, 12, 16 ] false + +Answer: 3) [ 2, 4, 8, 12, 16 ] true + +###9. What would be the output of following code? + +```javascript +(function(){ + var containers = [2,0,false,"", '12', true]; + var containers = containers.filter(Boolean); + console.log(containers); + var containers = containers.filter(Number); + console.log(containers); + var containers = containers.filter(String); + console.log(containers); + var containers = containers.filter(Object); + console.log(containers); +})(); +``` + +1. [ 2, '12', true ] + [ 2, '12', true ] + [ 2, '12', true ] + [ 2, '12', true ] +2. [false, true] + [ 2 ] + ['12'] + [ ] +3. [2,0,false,"", '12', true] + [2,0,false,"", '12', true] + [2,0,false,"", '12', true] + [2,0,false,"", '12', true] +4. [ 2, '12', true ] + [ 2, '12', true, false ] + [ 2, '12', true,false ] + [ 2, '12', true,false] + + +Answer: 1) [ 2, '12', true ] + [ 2, '12', true ] + [ 2, '12', true ] + [ 2, '12', true ] + +###10. What would be the output of following code? + +```javascript +(function(){ + var list = ['foo','bar','john','ritz']; + console.log(list.slice(1)); + console.log(list.slice(1,3)); + console.log(list.slice()); + console.log(list.slice(2,2)); + console.log(list); +})(); +``` + +1. [ 'bar', 'john', 'ritz' ] + [ 'bar', 'john' ] + [ 'foo', 'bar', 'john', 'ritz' ] + [] + [ 'foo', 'bar', 'john', 'ritz' ] +2. [ 'bar', 'john', 'ritz' ] + [ 'bar', 'john','ritz ] + [ 'foo', 'bar', 'john', 'ritz' ] + [] + [ 'foo', 'bar', 'john', 'ritz' ] +3. [ 'john', 'ritz' ] + [ 'bar', 'john' ] + [ 'foo', 'bar', 'john', 'ritz' ] + [] + [ 'foo', 'bar', 'john', 'ritz' ] +4. [ 'foo' ] + [ 'bar', 'john' ] + [ 'foo', 'bar', 'john', 'ritz' ] + [] + [ 'foo', 'bar', 'john', 'ritz' ] + +Answer: 1) [ 'bar', 'john', 'ritz' ] + [ 'bar', 'john' ] + [ 'foo', 'bar', 'john', 'ritz' ] + [] + [ 'foo', 'bar', 'john', 'ritz' ] + +###11. What would be the output of following code? + +```javascript +(function(){ + var list = ['foo','bar','john']; + console.log(list.splice(1)); + console.log(list.splice(1,2)); + console.log(list); +})(); +``` + +1. [ 'bar', 'john' ] [] [ 'foo' ] +2. [ 'bar', 'john' ] [] [ 'bar', 'john' ] +3. [ 'bar', 'john' ] [ 'bar', 'john' ] [ 'bar', 'john' ] +4. [ 'bar', 'john' ] [] [] + +Answer: 1. [ 'bar', 'john' ] [] [ 'foo' ] + +###12. What would be the output of following code? + +```javascript +(function(){ + var arrayNumb = [2, 8, 15, 16, 23, 42]; + arrayNumb.sort(); + console.log(arrayNumb); +})(); +``` + +1. [2, 8, 15, 16, 23, 42] +2. [42, 23, 26, 15, 8, 2] +3. [ 15, 16, 2, 23, 42, 8 ] +4. [ 2, 8, 15, 16, 23, 42 ] + +Answer: 3. [ 15, 16, 2, 23, 42, 8 ] + ## Function: ###1. What would be the output of following code ? @@ -1972,6 +2746,117 @@ console.log(obj.innerMessage()); 4. ReferenceError: this.message is not defined Answer: 3) undefined + +###5. What would the output of following code ? + +```javascript +var obj = { + message: 'Hello', + innerMessage: function () { + var self = this; + (function () { + console.log(self.message); + }()); + } +}; +console.log(obj.innerMessage()); +``` + +1. Type Error +2. 'Hello' +3. undefined +4. ReferenceError: self.message is not defined + +Answer: 2) 'Hello' + +###6. What would the output of following code ? + +```javascript +function myFunc(){ + console.log(this.message); +} +myFunc.message = "Hi John"; + +console.log(myFunc()); +``` + +1. Type Error +2. 'Hi John' +3. undefined +4. ReferenceError: this.message is not defined + +Answer: 3) undefined + +###7. What would the output of following code ? + +```javascript +function myFunc(){ + console.log(myFunc.message); +} +myFunc.message = "Hi John"; + +console.log(myFunc()); +``` + +1. Type Error +2. 'Hi John' +3. undefined +4. ReferenceError: this.message is not defined + +Answer: 2) 'Hi John' + +###8. What would the output of following code ? + +```javascript +function myFunc() { + myFunc.message = 'Hi John'; + console.log(myFunc.message); +} +console.log(myFunc()); +``` + +1. Type Error +2. 'Hi John' +3. undefined +4. ReferenceError: this.message is not defined + +Answer: 2) 'Hi John' + +###9. What would the output of following code ? + +```javascript +function myFunc(param1,param2) { + console.log(myFunc.length); +} +console.log(myFunc()); +console.log(myFunc("a","b")); +console.log(myFunc("a","b","c","d")); +``` + +1. 2 2 2 +2. 0 2 4 +3. undefined +4. ReferenceError + +Answer: a) 2 2 2 + +###10. What would the output of following code ? + +```javascript +function myFunc() { + console.log(arguments.length); +} +console.log(myFunc()); +console.log(myFunc("a","b")); +console.log(myFunc("a","b","c","d")); +``` + +1. 2 2 2 +2. 0 2 4 +3. undefined +4. ReferenceError + +Answer: 2) 0 2 4 ## Object Oriented @@ -1991,22 +2876,460 @@ Person.displayName = function(){ console.log(this.name); } -var person1 = new Person('Nishant'); +var person1 = new Person('John'); person1.displayName(); Person.displayName(); ``` -1. Nishant Person -2. Nishant John -3. Nishant undefined +1. John Person +2. John John +3. John undefined 4. John John -Answer: 1) Nishant Person +Answer: 1) John Person + +## Scopes + +###1. What would the output of following code ? + +```javascript +function passWordMngr() { + var password = '12345678'; + this.userName = 'John'; + return { + pwd: password + }; +} +// Block End +var userInfo = passWordMngr(); +console.log(userInfo.pwd); +console.log(userInfo.userName); +``` + +1. 12345678 Window +2. 12345678 John +3. 12345678 undefined +4. undefined undefined + +Answer: 3) 12345678 undefined + +###2. What would the output of following code ? + +```javascript +var employeeId = 'aq123'; +function Employee() { + this.employeeId = 'bq1uy'; +} +console.log(Employee.employeeId); +``` + +1. Reference Error +2. aq123 +3. bq1uy +4. undefined + +Answer: 4) undefined + +###3. What would the output of following code ? + +```javascript +var employeeId = 'aq123'; + +function Employee() { + this.employeeId = 'bq1uy'; +} +console.log(new Employee().employeeId); +Employee.prototype.employeeId = 'kj182'; +Employee.prototype.JobId = '1BJKSJ'; +console.log(new Employee().JobId); +console.log(new Employee().employeeId); +``` + +1. bq1uy 1BJKSJ bq1uy undefined +2. bq1uy 1BJKSJ bq1uy +3. bq1uy 1BJKSJ kj182 +4. undefined 1BJKSJ kj182 + +Answer: 2) bq1uy 1BJKSJ bq1uy + +###4. What would the output of following code ? + +```javascript +var employeeId = 'aq123'; +(function Employee() { + try { + throw 'foo123'; + } catch (employeeId) { + console.log(employeeId); + } + console.log(employeeId); +}()); +``` + +1. foo123 aq123 +2. foo123 foo123 +3. aq123 aq123 +4. foo123 undefined + +Answer: 1) foo123 aq123 + +## Call, Apply, Bind + +###1. What would the output of following code ? + +```javascript +(function() { + var greet = 'Hello World'; + var toGreet = [].filter.call(greet, function(element, index) { + return index > 5; + }); + console.log(toGreet); +}()); +``` + +1. Hello World +2. undefined +3. World +4. [ 'W', 'o', 'r', 'l', 'd' ] + +Answer: 4) [ 'W', 'o', 'r', 'l', 'd' ] + +###2. What would the output of following code ? + +```javascript +(function() { + var fooAccount = { + name: 'John', + amount: 4000, + deductAmount: function(amount) { + this.amount -= amount; + return 'Total amount left in account: ' + this.amount; + } + }; + var barAccount = { + name: 'John', + amount: 6000 + }; + var withdrawAmountBy = function(totalAmount) { + return fooAccount.deductAmount.bind(barAccount, totalAmount); + }; + console.log(withdrawAmountBy(400)()); + console.log(withdrawAmountBy(300)()); +}()); +``` + +1. Total amount left in account: 5600 Total amount left in account: 5300 +2. undefined undefined +3. Total amount left in account: 3600 Total amount left in account: 3300 +4. Total amount left in account: 5600 Total amount left in account: 5600 + +Answer: 1) Total amount left in account: 5600 Total amount left in account: 5300 + +###3. What would the output of following code ? + +```javascript +(function() { + var fooAccount = { + name: 'John', + amount: 4000, + deductAmount: function(amount) { + this.amount -= amount; + return this.amount; + } + }; + var barAccount = { + name: 'John', + amount: 6000 + }; + var withdrawAmountBy = function(totalAmount) { + return fooAccount.deductAmount.apply(barAccount, [totalAmount]); + }; + console.log(withdrawAmountBy(400)); + console.log(withdrawAmountBy(300)); + console.log(withdrawAmountBy(200)); +}()); +``` + +1. 5600 5300 5100 +2. 3600 3300 3100 +3. 5600 3300 5100 +4. undefined undefined undefined + +Answer: 1) 5600 5300 5100 + +###4. What would the output of following code ? + +```javascript +(function() { + var fooAccount = { + name: 'John', + amount: 6000, + deductAmount: function(amount) { + this.amount -= amount; + return this.amount; + } + }; + var barAccount = { + name: 'John', + amount: 4000 + }; + var withdrawAmountBy = function(totalAmount) { + return fooAccount.deductAmount.call(barAccount, totalAmount); + }; + console.log(withdrawAmountBy(400)); + console.log(withdrawAmountBy(300)); + console.log(withdrawAmountBy(200)); +}()); +``` + +1. 5600 5300 5100 +2. 3600 3300 3100 +3. 5600 3300 5100 +4. undefined undefined undefined + +Answer: 2) 3600 3300 3100 + +###5. What would the output of following code ? + +```javascript +(function greetNewCustomer() { + console.log('Hello ' + this.name); +}.bind({ + name: 'John' +})()); +``` + +1. Hello John +2. Reference Error +3. Window +4. undefined + +Answer: 1) Hello John + +###6. What would the output of following code ? + +```javascript +(function greetNewCustomer() { + console.log('Hello ' + this.name); +}.bind({ + name: 'John' +})()); +``` + +1. Hello John +2. Reference Error +3. Window +4. undefined + +Answer: 1) Hello John + +## Callback Function + +###1. What would the output of following code ? + +```javascript +function getDataFromServer(apiUrl){ + var name = "John"; + return { + then : function(fn){ + fn(name); + } + } +} + +getDataFromServer('www.google.com').then(function(name){ + console.log(name); +}); + +``` + +1. John +2. undefined +3. Reference Error +4. fn is not defined + +Answer: 1) John + +###2. What would the output of following code ? + +```javascript +(function(){ + var arrayNumb = [2, 8, 15, 16, 23, 42]; + Array.prototype.sort = function(a,b){ + return a - b; + }; + arrayNumb.sort(); + console.log(arrayNumb); +})(); + +(function(){ + var numberArray = [2, 8, 15, 16, 23, 42]; + numberArray.sort(function(a,b){ + if(a == b){ + return 0; + }else{ + return a < b ? -1 : 1; + } + }); + console.log(numberArray); +})(); + +(function(){ + var numberArray = [2, 8, 15, 16, 23, 42]; + numberArray.sort(function(a,b){ + return a-b; + }); + console.log(numberArray); +})(); +``` + +1. [ 2, 8, 15, 16, 23, 42 ] + [ 2, 8, 15, 16, 23, 42 ] + [ 2, 8, 15, 16, 23, 42 ] +2. undefined undefined undefined +3. [42, 23, 16, 15, 8, 2] + [42, 23, 16, 15, 8, 2] + [42, 23, 16, 15, 8, 2] +4. Reference Error + +Answer: 1) [ 2, 8, 15, 16, 23, 42 ] + [ 2, 8, 15, 16, 23, 42 ] + [ 2, 8, 15, 16, 23, 42 ] + +## Return Statement + +###1. What would the output of following code ? + +```javascript +(function(){ + function sayHello(){ + var name = "Hi John"; + return + { + fullName: name + } + } + console.log(sayHello().fullName); +})(); +``` + +1. Hi John +2. undefined +3. Reference Error +4. Uncaught TypeError: Cannot read property 'fullName' of undefined + +Answer: 4) Uncaught TypeError: Cannot read property 'fullName' of undefined + +###2. What would the output of following code ? + +```javascript +function getNumber(){ + return (2,4,5); +} + +var numb = getNumber(); +console.log(numb); +``` + +1. 5 +2. undefined +3. 2 +4. (2,4,5) + +Answer: 1) 5 + +###3. What would the output of following code ? + +```javascript +function getNumber(){ + return; +} + +var numb = getNumber(); +console.log(numb); +``` + +1. null +2. undefined +3. "" +4. 0 + +Answer: 2) undefined + +###4**. What would the output of following code ? + +```javascript +function mul(x){ + return function(y){ + return [x*y, function(z){ + return x*y + z; + }]; + } +} + +console.log(mul(2)(3)[0]); +console.log(mul(2)(3)[1](4)); +``` + +1. 6, 10 +2. undefined undefined +3. Reference Error +4. 10, 6 + +Answer: 1) 6, 10 + +###5**. What would the output of following code ? + +```javascript +function mul(x) { + return function(y) { + return { + result: x * y, + sum: function(z) { + return x * y + z; + } + }; + }; +} +console.log(mul(2)(3).result); +console.log(mul(2)(3).sum(4)); +``` + +1. 6, 10 +2. undefined undefined +3. Reference Error +4. 10, 6 + +Answer: 1) 6, 10 + +###6. What would the output of following code ? + +```javascript +function mul(x) { + return function(y) { + return function(z) { + return function(w) { + return function(p) { + return x * y * z * w * p; + }; + }; + }; + }; +} +console.log(mul(2)(3)(4)(5)(6)); +``` + +1. 720 +2. undefined +3. Reference Error +4. Type Error + +Answer: 1) 720 + + ## Have doubt in this question ?? -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) -## This Book will be completed by June 1 2016 and available to buy. If you want me to sent early copy of this book then please add your name and email address in google form here [Google Form](http://goo.gl/forms/QSpxVtvsNb). ##Contributing @@ -2015,7 +3338,7 @@ I'm always welcome to feedback on how the book can be improved, and more questio ####Note: All contributor to this book will be added as contributor in Book Last page by default, So if you have contributed and don't wanted to be included then please write an email to me at nihantanu@gmail.com ##For any other query: -[Schedule 15 min discussion with me for free @nishantk](http://www.canumeet.com/nishantk/javascript-interview-query-discussion) + ##License @@ -2024,4 +3347,4 @@ This book is released under a Creative Commons Attribution-Noncommercial- No Der What this means it that the project is free to read and use, but the license does not permit commercial use of the material (i.e you can freely print out the questions for your own use, but you can't sell it). I'm trying to best to publish all of my books in a free + purchased (if you would like to support these projects) form so I would greatly appreciate it if you would respect these terms. -Copyright Nishant Kumar, 2016. +Copyright Iurii Katkov and Nishant Kumar, 2017.