Saturday, April 28, 2018

JavaScript Introduction


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

Example
document.getElementById('demo').innerHTML = 'Hello JavaScript';
»                          
JavaScript Can Change HTML Attributes
This example changes an HTML image by changing the src (source) attribute of an <img> tag:

The Light Bulb
Turn on the light  Turn off the light
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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 = "25px";
or
document.getElementById('demo').style.fontSize = '25px';
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JavaScript accepts both double and single 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';
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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';

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