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ECMAScript 2015 - ES6

ECMAScript 6 was the second major revision to JavaScript.ECMAScript 6 is also known as ES6 and ECMAScript 2015.This chapter describes the most important features of ES6.
ECMAScript 2015 - ES6

New Features in ES6

  • JavaScript Arrow Functions
  • JavaScript For/of
  • JavaScript Classes
  • JavaScript Promises
  • Default Parameters

JavaScript Arrow Functions: Arrow functions allows a short syntax for writing function expressions.

You don't need the function keyword, the return keyword, and the curly brackets.

Example

// ES5
var x = function(x, y) {
return x * y;
}

// ES6
const x = (x, y) => x * y;

The For/Of Loop

The JavaScript for/of statement loops through the values of an iterable objects.

for/of lets you loop over data structures that are iterable such as Arrays, Strings, Maps, NodeLists, and more.

Example

var cars = ["BMW", "Volvo", "Mini"];
var x;

for (x of cars) {
 document.write(x + "<br >");
}

JavaScript Classes

JavaScript Classes are templates for JavaScript Objects.Use the keyword class to create a class.Always add a method named constructor().A JavaScipt class is not an object.

Syntax

class ClassName {
 constructor() { ... }
}

JavaScript Promises

A Promise is a JavaScript object that links "Producing Code" and "Consuming Code".

"Producing Code" can take some time and "Consuming Code" must wait for the result.

Example

let myPromise = new Promise(function(myResolve, myReject) {
// "Producing Code" (May take some time)

 myResolve(); // when successful
 myReject();  // when error
});

// "Consuming Code" (Must wait for a fulfilled Promise).
myPromise.then(
function(value) { /* code if successful */ },
function(error) { /* code if some error */ }
);

Default Parameter Values:ES6 allows function parameters to have default values.
Example

function myFunction(x, y = 10) {
// y is 10 if not passed or undefined
return x + y;
}
myFunction(5); // will return 15

JavaScript ES6
https://www.w3schools.com/js/js_es6.asp#mark_rest

#JavaScript #ES6 #ECMAScript #Promise #Probyto #ProbytoAI

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