Advantages and disadvantages of client-side scripts

Developers might consider using client-side scripts for many reasons, and they might have some legitimate reasons not to use them.

Advantages

• Allow for more interactivity by immediately responding to users' actions
• Execute quickly because they don't require a trip to the server
• May improve the usability of Web sites for users whose browsers support scripts
• Can give developers more control over the look and behavior of their Web widgets (note that this can be an advantage or disadvantage)
• Can be substituted with alternatives (for example, HTML) if users' browsers do not support scripts
• Are reusable and obtainable from many free resources such as Hotscripts.com and Javascript.com (see Resources)

Disadvantages

Client-side scripts also create additional worries, including:

• Not all browsers support scripts, therefore, users might experience errors if no alternatives have been provided
• Different browsers and browser versions support scripts differently, thus more quality assurance testing is required
• More development time and effort might be required (if the scripts are not already available through other resources)
• Developers have more control over the look and behavior of their Web widgets; however, usability problems can arise if a Web widget looks like a standard control but behaves differently or vice-versa

General usability considerations

Before we look at specific examples of Web widgets that utilize client-side scripts, here are some general usability considerations to keep in mind:

• Research what scripts work best with the browsers your audience is likely to use. JavaScript is probably the most widely supported scripting language used today. It is compatible with the two most popular browsers -- Microsoft Internet Explorer (IE) and Netscape. Alternatives to JavaScript, like Microsoft's VBScript, will also work but usually only on Internet Explorer.
• If your audience includes PC and Mac users, be sure to test your scripts on browsers for both platforms. The Mac versions of some browsers do not support scripts as well as the PC versions.
• Test your scripts on at least the previous two versions of those browsers your audience will use. Many people are slow to update their browsers; therefore the latest scripts might not work for these individuals. At the time of this writing, statistics indicate that 57% of Internet users use IE 5.0 and 30% use IE 6.0 (see Resources). Companies like Netscape also provide information for developers on their Web site about known bugs.
• Web sites should still be readable and function properly without scripts. In this competitive marketplace, Web site owners can't afford to turn away members of their target audience who might have incompatible browsers. It is the developer's responsibility to build a site that works for the widest audience possible.