JavaScript

JavaScript is a programming language used for web development. While it is primarily used as a scripting language, it has some object-oriented features.[1] It is used mainly[2] for client-side programming; for a good server-side language, see PHP. In a web browser, JavaScript has access to the content of HTML documents.[3]

## Contents

* 1 Arrays
* 2 Visibility of class members
* 2.1 Accessing public and private variables
* 3 Example Code
* 4 Notes
* 5 External links

## Arrays[edit]

JavaScript doesn't have the same kind of arrays as Java; this is one of the differences between the two languages. In JavaScript, the standard array notation is used, but internally data is stored in a hash table.

## Visibility of class members[edit]

There are two sets of variables associated with any object you define in JavaScript. The first set of variables defined with the `this` keyword, are all public. The second set of variables, defined with the `var` keyword, are private. You can even use the same name for a public and private variable, and JavaScript can tell them apart.

### Accessing public and private variables[edit]

Use regular dot notation to get the public variables of an object

* shape.size

Within class functions, use this to get a public variable, and omit to get a private variable!

## Example Code[edit]

The following example can be used to disable a form button, for example, to prevent double-posting on a forum.

// Following code licensed CC-SA

function ref(object)

if (document.getElementById) { return document.getElementById(object); }
else if (document.all) { return eval('document.all.' + object); }
else { return false; }

function setButton(btnObject)

if ( document.post.btnName && document.post.btnValue )

document.post.btnName.value = btnObject.name;
document.post.btnValue.value = btnObject.value;

else if ( document.all.btnName && document.all.btnValue )

document.all.btnName.value = btnObject.name;
document.all.btnValue.value = btnObject.value;

var postForm = ref('post');
postForm.submit();
return true;

To make use of this function, add it to the JavaScript used by your form, and then add the following to the button you wish to disable:

onClick="setButton(this);"

## Notes[edit]

1. ↑ Object Oriented Programming in JavaScript \- Mike Koss
2. ↑ For server side and desktop usage see http://vertx.io/ and http://nodejs.org/
3. ↑ David Flanagan, Javascript: The definitive guide, page 6

## External links[edit]

* Javascript Tutorial