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().
The example below "finds" 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
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 = "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";
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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";
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Did You Know?
JavaScript and Java are completely different languages, both in concept
and design.
JavaScript was invented by Brendan Eich in 1995, and became an ECMA standard
in 1997.
ECMA-262 is the official name of the standard. ECMAScript is the official name of the language.
JavaScript Versions »
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Reference: https://www.w3schools.com/js/js_intro.asp