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JS Tutorial

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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";
Try it Yourself »

With HTML and JavaScript you can use single or double quotes:

Example

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

JavaScript Can Change HTML Attributes

This example changes an HTML image by changing 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 = "25px";
or
document.getElementById('demo').style.fontSize = '25px';
Try it Yourself »

JavaScript accepts both doubble and sigle quotes


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