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JS Forms

JS Forms Forms API

JS Objects

Object Definitions Object Properties Object Methods Object Display Object Accessors Object Constructors Object Prototypes Object ECMAScript 5

JS Functions

Function Definitions Function Parameters Function Invocation Function Call Function Apply Function Closures

JS Classes

Class Intro Class Inheritance Class Static

JS Async

JS Callbacks JS Asynchronous JS Promises JS Async/Await

JS HTML DOM

DOM Intro DOM Methods DOM Document DOM Elements DOM HTML DOM CSS DOM Animations DOM Events DOM Event Listener DOM Navigation DOM Nodes DOM Collections DOM Node Lists

JS Browser BOM

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JS AJAX

AJAX Intro AJAX XMLHttp AJAX Request AJAX Response AJAX XML File AJAX PHP AJAX ASP AJAX Database AJAX Applications AJAX Examples

JS JSON

JSON Intro JSON Syntax JSON vs XML JSON Data Types JSON Parse JSON Stringify JSON Objects JSON Arrays JSON PHP JSON HTML JSON JSONP

JS Web APIs

Web API Intro Web History API Web Storage API Web Geolocation API

JS vs jQuery

jQuery Selectors jQuery HTML jQuery CSS jQuery DOM

JS Examples

JS Examples JS HTML DOM JS HTML Input JS HTML Objects JS HTML Events JS Browser JS Editor JS Exercises JS Quiz JS Certificate

JS References

JavaScript Objects HTML DOM Objects


ECMAScript 2017

The JavaScript naming convention started with ES1, ES2, ES3, ES5 and ES6.

But, ECMAScript 2016 and 2017 was not called ES7 and ES8.

Since 2016 new versions are named by year (ECMAScript 2016, ECMAScript 2017).

New Features in ECMAScript 2017

This chapter introduces the new features in ECMAScript 2017

  • JavaScript String padding
  • JavaScript Object.entries
  • JavaScript Object.values
  • JavaScript async functions
  • JavaScript shared memory

JavaScript String Padding

ECMAScript 2017 added two String methods: padStart and padEnd to support padding at the beginning and at the end of a string.

Example

let str = "5";
str = str.padStart(4,0);
// result is 0005
Try it Yourself »

Example

let str = "5";
str = str.padEnd(4,0);
// result is 5000
Try it Yourself »

Firefox and Safari were the first browsers with support for JavaScript string padding:

Chrome 57 Edge 15 Firefox 48 Safari 10 Opera 44
Mar 2017 Apr 2017 Aug 2016 Sep 2016 Mar 2017

JavaScript Object Entries

ECMAScript 2017 adds a new Object.entries method to objects:

Example

const person = {
  firstName : "John",
  lastName : "Doe",
  age : 50,
  eyeColor : "blue"
};
document.getElementById("demo").innerHTML = Object.entries(person);
Try it Yourself »

Chrome and Firefox were the first browsers with support for Object.entries:

Chrome 47 Edge 14 Firefox 47 Safari 10.1 Opera 41
Jun 2016 Aug 2016 Jun 2016 Mar 2017 Oct 2016

JavaScript Object Values

Object.values are similar to Object.entries, but returns a single dimension array of the object values:

Example

const person = {
  firstName : "John",
  lastName : "Doe",
  age : 50,
  eyeColor : "blue"
};
document.getElementById("demo").innerHTML = Object.values(person);
Try it Yourself »

Firefox and Chrome were the first browsers with support for Object.values:

Chrome 54 Edge 14 Firefox 47 Safari 10.1 Opera 41
Oct 2016 Aug 2016 Jun 2016 Mar 2017 Oct 2016


JavaScript Async Functions

Waiting for a Timeout

async function myDisplay() {
  let myPromise = new Promise(function(myResolve, myReject) {
    setTimeout(function() { myResolve("I love You !!"); }, 3000);
  });
  document.getElementById("demo").innerHTML = await myPromise;
}

myDisplay();

Try it Yourself »

Firefox and Chrome were the first browsers with support for async JavaScript functions:

Chrome 55 Edge 15 Firefox 52 Safari 11 Opera 42
Des 2016 Apr 2017 Mar 2017 Sep 2017 Des 2016