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23.3. Browser Support

Versions 2.0 and higher of both Netscape Navigator and Microsoft Internet Explorer have some degree of support for GIF animation, with the implementation improving with each subsequent release. Still, there are a few specific aspects of animation that prove to be particularly problematic for some early-version and lesser-known browsers.

If your animation uses one of the following, you may want to do some cross-browser, cross-platform testing:


Very early browsers do not support looping at all. More commonly, looping is supported, but settings for a specific number of loops may be ignored. If you specify the number of repetitions, be aware that some users will experience nonstop looping instead. Internet Explorer Versions 2 and 3 support only one-loop animation.

Revert to previous

This disposal method does not work on Navigator 2.0, 3.0, and the Mac version of 4.0 (it treats it as "do not dispose.") (See Section 23.5.3, "Disposal Methods" later in this chapter.) Revert to Previous is supported only by Internet Explorer Versions 3.0 and higher. Although it can result in slightly smaller file sizes, it is recommended to avoid this setting. This and other disposal methods are more thoroughly discussed later in this chapter.

Browsers that do not support GIF animation display a static image. The problem is that some browsers display the first frame and others display the last frame. If possible, it is advisable to make both your first and last frames meaningful (particularly if it contains important information, like the name of your company).

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