JavaScript Introduction
JavaScript is the world’s most popular programming language.
It is the language for HTML, for the web, for servers, PCs, laptops, tablets, phones, and more.
JavaScript is a Scripting Language
A scripting language is a lightweight programming language.
JavaScript is programming code that can be inserted into HTML pages.
JavaScript code can be executed by all modern web browsers.
JavaScript is easy to learn.l.
JavaScript: Writing Into HTML Output
Example
document.write(“<p>This is a paragraph</p>”);
| – | You can only use document.write in the HTML output. If you use it after the document has loaded, the whole document will be overwritten. |
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JavaScript: Reacting to Events
Example
The alert() function is not much used in JavaScript, but it is quite handy for trying out code.
The onclick event is only one of the many HTML events you will learn about in this tutorial.
JavaScript: Changing HTML Content
Using JavaScript to manipulate the content of HTML elements is very common.
Example
x.innerHTML=”Hello JavaScript”; //Change the content
You will often see document.getElementById(“some id“). This is defined in the HTML DOM.
The DOM (Document Object Model) is the official W3C standard for accessing HTML elements.
You will find several chapters about the HTML DOM in this tutorial.
JavaScript: Changing HTML Styles
Changing the style of an HTML element, is a variant of changing an HTML attribute.
Example
x.style.color=”#ff0000″; //Change the style
JavaScript: Validate Input
JavaScript is commonly used to validate input.
Example
Did You Know?
| – | JavaScript and Java are two completely different languages, in both concept and design. Java (invented by Sun) is a more complex programming language in the same category as C.ECMA-262 is the official name of the JavaScript standard.JavaScript was invented by Brendan Eich. It appeared in Netscape (a no longer existing browser) in 1995, and has been adopted by ECMA (a standard association) since 1997. |
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