Javascript array methods

forEach-sigature.js

arr.forEach(callback, [, thisArg]);
// thisArg is optional for forEeach

// the callback has the following arguments in forEach.
callback(currentValue, [, index [, array]])
// index and array are optional

foreach.js

const names =["Javascript", "Python", "PHP", "Flutter"];
names.forEach(name => {
	console.log(name);
});

// OUTPUT
// > Javascript
// > Python
// > PHP
// > Flutter

map-signature.js

let newArray = arr.map(callback, [, thisArg]); // thisArg is optional
callback(currentValue, [, index, [, array]]); // index and array are optional

// the callback must return an element for the new array after applying any transformation

map.js

const names =["Javascript", "Python", "PHP", "Flutter"];
const newNames = names.map((name, index) => {
	return index.toString() + '. ' +name;
});
console.log(newNames);
// OUTPUT : Array ["0. Javascript", "1. Python", "2. PHP", "3. Flutter"]