JavaScript Introduction

JavaScript is the most popular programming language in the world.

It is the language for HTML, for the Web, for computers, servers, laptops, tablets, smart phones, and more.

This page contains some examples of what JavaScript can do in HTML.

JavaScript Can Change HTML Elements

The HTML DOM (the Document Object Model) is the official W3C standard for accessing HTML elements.

JavaScript can manipulate the DOM (change HTML contents).

The following example changes the content (innerHTML) of an HTML element identified with id="demo":

Example

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

The method document.getElementById() is one of many methods in the HTML DOM.

You can use JavaScript to:

There are several chapters, about the HTML DOM, later in this tutorial.

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";

With JavaScript, you can change almost any CSS values.

Did You Know?

	JavaScript and Java are two completely different languages, both in concept and design. JavaScript was invented by Brendan Eich, to be used in Netscape (a no longer existing browser) in 1995, and was adopted by the ECMA standard association in 1997. ECMA-262 is the official name. ECMAScript 5 (version 1.8.5 - July 2010) is the latest standard.

Dhaval Thummar (dp)