Basic of JavaScript ✅

suhailroushan13 · suhailroushan13 · commit bdef2719ca1c · 2022-04-24T04:09:02.000+05:30
diff --git a/1. Intro to JavaScript/Introduction to JavaScript.pdf b/1. Intro to JavaScript/Introduction to JavaScript.pdf
diff --git a/2. Basic of JavaScript/1.js b/2. Basic of JavaScript/1.js
@@ -0,0 +1,24 @@
+//  To Print Output in Console
+
+console.log("Hello World");
+
+// Where you can use Single Qoutes or Double Qoutes
+
+console.log("Working In Single Quotes");
+console.log("Working In Double Quotes");
+
+// Output
+// Working In Single Quotes
+// Working In Double Quotes
+
+// In JavaScript Semi-Colon (;) is not required after the last statement in a line. Its is Optional in JavaScript.
+
+// Both Are Same
+// But Having Semi-Colon is a Good Practice;
+console.log("With Semicolon");
+console.log("Without Semicolon");
+
+// To Run This File
+// node fileName.js
+// node 1.js
+
diff --git a/2. Basic of JavaScript/10.js b/2. Basic of JavaScript/10.js
@@ -0,0 +1,28 @@
+//  2. Function Scope
+console.log("FUNCTION SCOPE");
+
+// This Works
+function scope() {
+  const constB = "const";
+  var varB = "var";
+  let letB = "let";
+
+  console.log(varB);
+  console.log(letB);
+  console.log(constB);
+}
+scope();
+
+/// But Not This
+// function scope() {
+//   const constB = "const";
+//   var varB = "var";
+//   let letB = "let";
+
+// }
+// scope();
+// console.log(varB);
+// console.log(letB);
+// console.log(constB);
+
+// This will give a Error
diff --git a/2. Basic of JavaScript/11.js b/2. Basic of JavaScript/11.js
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+function box() {
+  var a = "i am a";
+  console.log("Function Scope");
+  console.log(a);
+}
+box();
+
+// Here Var a is working inside function scope
+
+// function box() {
+//   var a = "i am a";
+//   console.log("Function Scope");
+// }
+// box();
+// console.log(a);
+
+// VAR USES
+
+// 1. but if var is in a function scope ...then it can be only available in that function scope
+// 2. if var is in global scope ...then it can be available in all the function scope and global scope
+// 3. if var is in a function scope ..it will become function scope variable
+// 4. if var is in a function scope .. you can acces it inside that function scope at any block...inside that function scope // Having it Multiple blocks
+// 5. Var allows you to re declare the same variable
+
+// LET USES
+
+// 1. let can only be used in a block scope
+// 2. if let is in a function scope ...then it can be only available in that function scope
+// 3. if let is in global scope ...then it can be available in all the global scope but not in function scope
+// 4. let will dont allow you to redeclare the same variable
+
+// let a = "hello;
+// let a = "bye"; // Error a is re declared
+
+//  But you can have this
+//  let a = "hello";
+//  a = "bye";
+// console.log(a) ; // This will work
+
+// let a = 'hello';
+
+// function box() {
+//     // console.log(a);
+//     console.log("Function Scope");
+// }
+
+// console.log(a);
+
+// CONST USES
+// const c = 'hello';
+// c =  'bye'; // Error c is a constant variable
+
+//  1. const is a constant variable
+// 2. const is a block scope variable
+// 3. const will not work out of the function scope
+// 4. const will not allow you to redeclare the same variable
+// 5. const will not allow you to reassign the same variable
+// const cc = 'cc'
+
+// function box() {
+//     console.log('Const Scope');
+
+//     console.log(cc);
+// }
+// box();
+// Output: cc
+
+// If const is declared outside .....you can still access inside the function
+// If const is declared inside .....you can not access outside the function
diff --git a/2. Basic of JavaScript/2.js b/2. Basic of JavaScript/2.js
@@ -0,0 +1,19 @@
+console.log("How To Comment in JavaScript");
+
+
+// For Single Line Comment
+
+// For Multiple Line Comment
+// /*     */
+
+
+console.log("For Multiple Line Comment Using /* */");
+
+/*
+console.log("1");
+console.log("2");
+console.log("3");
+console.log("4");
+console.log("5");
+
+*/
diff --git a/2. Basic of JavaScript/3.js b/2. Basic of JavaScript/3.js
@@ -0,0 +1,23 @@
+// What is Variable ?
+/*
+    Variable is a container for storing data values.
+    Variable can be used to store data values.
+    Variable is a name given to a memory location.
+    We Can use the information stored in a variable to perform a task.
+    We can use the same variable name to refer to different values.
+    We can change the data of information later     
+*/
+
+// Declaring Variables Using var
+
+var firstName = "Suhail Roushan";
+
+console.log(firstName);
+
+// Output : Suhail Roushan
+
+// JavaScript is Case Sensitive
+// hello is not equal to Hello
+
+firstName = "JavaScript";
+console.log(firstName);
diff --git a/2. Basic of JavaScript/4.js b/2. Basic of JavaScript/4.js
@@ -0,0 +1,18 @@
+// By Default If you didnt declare var it will take global variable as var
+
+var home = "ROOM";
+home = "ROOM";
+
+// Both are Same
+
+// By default it takes variable as global variable as var
+
+// Ruling for Naming Variables
+// 1. Variable names can only contain letters, numbers, and underscores.
+// 2. Variable names are case sensitive.
+// 3. Variable names should not be JavaScript keywords.
+// Keywords are var , let , const
+// 4. Variable names should not start with a number.
+// 5. Use meaningful names in variables
+// 6. Use CamelCase for naming variables
+
diff --git a/2. Basic of JavaScript/5.js b/2. Basic of JavaScript/5.js
@@ -0,0 +1,29 @@
+// JavaScript is a Interpreted Language
+// Where you can perform Calculations
+
+var add = 10 + 12
+console.log(add);
+// Output :- 22
+
+var sub = 10 - 12
+console.log(sub);
+// Output :- -2
+
+var mul = 10 * 12
+console.log(mul);
+// Output :- 120
+
+var div = 10 / 2
+console.log(div);
+// Output :- 5
+
+// In Any Programming Language % is not Percenatge its Modules
+// 10 % 2 = 0
+// The Left ones after Dividing
+// 10 % 3 = 1
+// AAA AAA AAA A 
+//  The Left one is 1 so 10%3 = 1
+var mod = 10 % 2
+console.log(mod);
+// Output :- 0
+
diff --git a/2. Basic of JavaScript/6.js b/2. Basic of JavaScript/6.js
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+// Power and Square root
+
+
+// For Power of 2
+
+var a = 2
+console.log(a ** 3);
+// Output :- 8
+// Its 2 power 3
+
+// For Square Root
+
+var b = 16
+console.log(Math.sqrt(b));
+// Output :- 4
+// Its Square Root of 16
+// OR
+console.log(b ** 0.5);
+
diff --git a/2. Basic of JavaScript/7.js b/2. Basic of JavaScript/7.js
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+// You can use _ in variable names in start or in middle
+// You can use $ in variable names in start or in middle
+
+// All are Valid
+var _suhail = "Hello, world!";
+var suh_ail = "Hello, world!";
+var $suhail = "Hello, world!";
+var suh$ail = "Hello, world!";
+var suhail = "Hello, world!";
+
+// Spaces are not valid in Variable names
+
+// var su hail = "Hello, world!"; // Not Allowed
+
+// Always use CamelCase
+
+// Example : firstPerson = "Suhail";
+// Example : firstName = "Suhail";
+// Example : first_person = "Suhail";
+// Example : first_person_name = "Suhail";
+// Example : first_person_name_age = "Suhail";
+// Example : first_person_name_age_height = "Suhail";
+// Example : first_person_name_age_height_weight = "Suhail";
diff --git a/2. Basic of JavaScript/8.js b/2. Basic of JavaScript/8.js
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+// Decalring Variables Using keyword let
+
+let firstName = "Suhail";
+let lastName = "Roushan";
+let age = "21";
+let height = "5.8";
+let weight = "60";
+let eyeColor = "Brown";
+let hairColor = "Black";
+let address = "Kathmandu";
+let city = "Kathmandu";
+let state = "Bagmati";
+let zipCode = "44600";
+let country = "Nepal";
+let phone = "9841234567";
+
+
diff --git a/2. Basic of JavaScript/9.js b/2. Basic of JavaScript/9.js
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+// Difference Between var and let and const
+
+// VAR
+
+// Use of this keyword without varibale declaration is a default of var
+
+//  var name = 'Jack';
+//  name = 'Jack' // But this is not a good practice and its deprecated
+
+// 1.Scoping
+// 2. Reassignment
+// 3. When we access a vaiable without declaring
+
+
+
+// 1. Scoping
+//  What is the scope of a variable?
+// 
+//  There are three types of scope
+// 1. Block Scope
+// 2. Function Scope
+// 3. Global Scope
+
+// 1. Block Scope
+{
+    var x = 'Hello';
+}
+
+// 2. Function Scope
+function scope() {
+    var x = 'Hello';
+}
+
+// 3. Global Scope
+var global = 'I am Global'
+
+
+// VAR USES
+
+// 1. but if var is in a function scope ...then it can be only available in that function scope
+// 2. if var is in global scope ...then it can be available in all the function scope and global scope
+// 3. if var is in a function scope ..it will become function scope variable
+// 4. if var is in a function scope .. you can acces it inside that function scope at any block...inside that function scope // Having it Multiple blocks
+// 5. Var allows you to re declare the same variable
+ 
+// WHY NOT TO USE VAR
+//  1. It is not a good practice to use var
+//  2. IF You asssign a value to a variable using var, it will be accessible in the global scope
+// 3. If you assign var i = 1 and same let i = 1 and then it will be conflict with let
+// 4. If you use var in a loop, it will be accessible in the global scope
+// 5. Because the let i will be print everywhere out of the block as it is having the previous value of i from var 
+// 6 So let will become a global varibale...if u have same varibale using let and var
+// 7. So Stop using var to declare variables
