JavaScript is a very flexible client-side scripting language that adds interactive features to a Web page. A client-side language runs in a user’s browser. Although JavaScript can also be used as a server-side language (runs on a Web server), it’s primary use in Web development is to add interactive features, such as HTML form input validation, image swapping, mouse rollover effects, drop-down navigational menus, moving objects and other interesting effects, to the user experience.

New programming technologies that require JavaScript to be enabled include Ajax. Other web site designs require that JavaScript be turned on in order for a site to function properly. This is most common is site designs that use drop-down JavaScript menus. You may therefore need to provide your users with instructions to allow them to enable JavaScript if they have previously disabled it.

For various reasons, some users turn off or disable JavaScript in their browsers either intentionally or accidentally. Depending upon whose statistics you want to believe, 5% to 10% of Internet users may have JavaScript disabled in their browsers. This can leave some sites in a non-functional or non-navigable state for those users. For obvious reasons, it is generally not a considered to be a good idea to require users to have JavaScript turned on to use a site. However, if your web site does require JavaScript to be enabled, here is how to do it.

The following instructions show how to turn on or enable JavaScript in various popular browsers in PCs using Windows. The instructions may vary slightly for users with Macintosh computers.

Mozilla FireFox 2.x

1. select Options in the Tools menu
2. Select the Content tab
3. check the box next to Enable JavaScript
4. click OK to close the Options dialogue box
5. click the browser’s Reload Current Page button

Netscape 7.x / Mozilla 1.x

1. select Preferences in the Edit menu
2. click Advanced on the left menu
3. select Scripts & Plugins from the sub-menu
4. on the top right side of the dialog box, check Enable JavaScript for Navigator
5. click OK to close the Preferences dialogue box
6. click the browser’s Reload Current Page button

Netscape 6.x / pre Mozilla 1.0

1. select Preferences in the Edit menu
2. click Advanced on the left menu
3. on the top right side of the dialog box, check Enable JavaScript for Navigator
4. click the browser’s Reload Current Page button

Internet Explorer 5.x, 6.x and 7.x

1. select Internet Options from the Tools menu
2. click the Security tab
3. click Custom level in Security Level for This Zone
4. scroll down to Scripting near the bottom
5. under Active Scripting, choose Enable
6. click OK to leave the Security Settings dialogue box
7. click OK to leave the Internet Options dialogue box
8. click the browser’s Refresh button

Be aware that any time a user sets Internet Explorer’s browser security to High, they disable all active scripting, which includes JavaScript.

To disable JavaScript, just follow the same instructions, but make sure that the appropriate checkbox in unchecked in each browser.