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Cross-browser refers to the ability of a website, web application, HTML construct or client-side script to function in environments that provide its required features and to bow out or degrade gracefully when features are absent or lacking. == Cross-browser vs. multi-browser == With regard to scripts, which is the most common usage, the term cross-browser is often confused with multi-browser (see jQuery). Multi-browser scripts can only be expected to work in environments where they have been demonstrated to work (due to assumptions based on observing a subset of browsers). Most publicly available libraries and frameworks are multi-browser scripts and list the environments (typically popular browsers in use at the time and in their default configurations) where they can be expected to work. Multi-browser scripts virtually always approach obsolescence as new browsers are introduced, features are deprecated and removed, and the authors assumptions are invalidated; therefore, multi-browser scripts have always required periodic maintenance. As the number of browsers and configurations in use has grown, so has the frequency of such maintenance. Older (or otherwise lesser) browsers and browser versions are periodically dropped as supported environments, regardless of whether or not they are still in use and without concern for what the new scripts will do when exposed to these environments. A typical scenario has them fail (e.g. by throwing an exception during initialization) in ways that were never anticipated by the authors, possibly rendering the document's content inaccessible. Scripts are categorized as cross-browser or multi-browser based on their logic. A script that uses cross-browser techniques (e.g. appropriate feature detection and testing) is cross-browser forever. Multi-browser scripts (which often rely on browser sniffing) remain multi-browser scripts until they fade away. No amount of testing can distinguish between cross-browser and multi-browser scripts; it is all in the code. Scripted cross-browser documents and applications must have content that is accessible when scripting is disabled or unavailable, else there would be no usable fallback for the scripts. For some applications (e.g., word processors, games), the fallback content is often little more than a description of what the user would see if scripting were available, as opposed to an empty document or lone error message. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cross-browser」の詳細全文を読む スポンサード リンク
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