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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 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 Constructors Object Prototypes

JS Functions

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

JS HTML DOM

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JS AJAX

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JS JSON

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JS Examples

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JS References

JavaScript Objects HTML DOM Objects


JavaScript Introduction


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";
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JavaScript accepts both double and single quotes:

Example

document.getElementById('demo').innerHTML = 'Hello JavaScript';
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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

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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";
or
document.getElementById('demo').style.fontSize = '35px';
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JavaScript Can Hide HTML Elements

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

Example

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