Javascript example of closure

js-closure-example.js

Array.prototype.myEach = function(callback) {
	for (let i = 0; i < this.length; i++) {
		callback(this[i]);
	}
}

Array.prototype.myMap = function(callback) {
	let newArray = []
	const collect = function(el) {
		newArray.push(callback(el))
	}
	
	this.myEach(collect)
	return newArray;
}

const cb = function(e) {
	return 2*e
}

console.log([1,2,3,4].myMap(cb))