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JS Tutorial

JS HOME JS Introduction JS Where To JS Output JS Statements JS Syntax JS Comments JS Variables JS Operators JS Arithmetic JS Assignment JS Data Types JS Functions JS Objects JS Events JS Strings JS String Methods JS Numbers JS Number Methods JS Arrays JS Array Methods JS Array Sort JS Array Iteration JS Dates JS Date Formats JS Date Get Methods JS Date Set Methods JS Math JS Random JS Booleans JS Comparisons JS Conditions JS Switch JS Loop For JS Loop While JS Break JS Type Conversion JS Bitwise JS RegExp JS Errors JS Scope JS Hoisting JS Strict Mode JS this Keyword JS Let JS Const JS Arrow Function JS Classes JS Debugging JS Style Guide JS Best Practices JS Mistakes JS Performance JS Reserved Words JS Versions JS Version ES5 JS Version ES6 JS JSON

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 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

JS Window JS Screen JS Location JS History JS Navigator JS Popup Alert JS Timing JS Cookies

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 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 Exercises JS Quiz JS Certificate

JS References

JavaScript Objects HTML DOM Objects


JavaScript Introduction

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This page contains some examples of what JavaScript can do.

JavaScript Can Change HTML Content

One of many JavaScript HTML methods is getElementById().

This example uses the method to "find" an HTML element (with id="demo") and changes the element content (innerHTML) to "Hello JavaScript":

Example

document.getElementById("demo").innerHTML = "Hello JavaScript";
Try it Yourself »

JavaScript accepts both double and single quotes:

Example

document.getElementById('demo').innerHTML = 'Hello JavaScript';
Try it Yourself »

JavaScript Can Change HTML Attribute Values

In this example JavaScript changes the value of the src (source) attribute of an <img> tag:

The Light Bulb

Try it Yourself »

JavaScript Can Change HTML Styles (CSS)

Changing the style of an HTML element, is a variant of changing an HTML attribute:

Example

document.getElementById("demo").style.fontSize = "35px";
Try it Yourself »

JavaScript Can Hide HTML Elements

Hiding HTML elements can be done by changing the display style:

Example

document.getElementById("demo").style.display = "none";
Try it Yourself »

JavaScript Can Show HTML Elements

Showing hidden HTML elements can also be done by changing the display style:

Example

document.getElementById("demo").style.display = "block";
Try it Yourself »

Commonly Asked Questions

  • How do I get JavaScript?
  • Where can I download JavaScript?
  • Is JavaScript Free?

You don't have to get or download JavaScript.

JavaScript is already running in your browser on your computer, on your tablet, and on your smart-phone. Free to use for everyone.
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