Create promisesLastName.js

Author: theprogrammedwords

Javascript/promisesLastName.js

@@ -0,0 +1,87 @@
+/*Promises in Javascript
+A promise is an object that may produce a single value some time in the future: either a resolved value, or a reason that it’s not resolved (e.g., a network error occurred). A promise may be in one of 3 possible states: fulfilled, rejected, or pending. Promise users can attach callbacks to handle the fulfilled value or the reason for rejection.
+
+
+
+Problem Description
+Given as inputs to the getLastNames() function
+
+A string representing a first name, firstName.
+An Array of person objects with properties, "firstName" and “lastName”
+
+
+Return a JavaScript Promise which is either
+rejected with a message "Invalid" if none of the person objects “firstName” property matches the input first name, firstName
+resolved with an sorted Array of "lastName" property values of objects whose “firstName” property matches the given first name, firstName
+
+Note
+
+The "lastName"s array should be sorted in alphabetical order
+
+Function to return a Promise object and not a String or Array
+*/
+
+function getLastNames(firstName, people) {
+
+        return new Promise(function (resolve, reject) {
+            let matchingPeeps = [];
+            matchingPeeps = people.filter((obj) => {
+                return obj.firstName === firstName
+            })
+            
+            if (matchingPeeps.length === 0) {
+                reject("Invalid");
+            } else {
+                let unsortedArray = [];
+
+                for (let i = 0; i < matchingPeeps.length; i++) {
+                    let lastName = matchingPeeps[i].lastName;
+                    unsortedArray.push(lastName);
+                }
+                unsortedArray.sort();
+                resolve(unsortedArray);
+            }
+            })
+}
+
+
+let firstName = 'David'
+
+people = [
+
+    {
+
+        firstName: 'David',
+
+        lastName: 'Dobrick'
+
+    },
+
+    {
+
+        firstName: 'David',
+
+        lastName: 'Beckham'
+
+    },
+
+    {
+
+        firstName: 'Chris',
+
+        lastName: 'Lee'
+
+    },
+
+    {
+
+        firstName: 'James',
+
+        lastName: 'Bond'
+
+    },
+
+]
+
+console.log(getLastNames(firstName, people))
+module.exports = getLastNames;