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使用 SWFObject 进行 Flash 检测

发布于 2024-08-08 04:26:12 字数 222 浏览 3 评论 0原文

我不太明白 http://download.macromedia.com/pub/developer/alternative_content_examples.zip'> 这里下载的 SWFObject 示例。

为什么仅通过以下方式检查 Flash 插件的可用性 <|--[if !IE]> -->指示。是不是说只有IE浏览器可以不预装flash播放器？当然不。那为什么只检查IE？

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奢欲 2024-08-15 04:26:12

不！该代码并不意味着它只检查 IE。

zip 中有两个示例，第一个是

<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="728" height="90" id="myFlashContent">
    <param name="movie" value="banner.swf" />
    <!--[if !IE]>-->
    <object type="application/x-shockwave-flash" data="banner.swf" width="728" height="90">
    <!--<![endif]-->
        <img src="banner.jpg" alt="Alternative content rules!" />
    <!--[if !IE]>-->
    </object>
    <!--<![endif]-->
</object>

第二个：

<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="480" height="270" id="myFlashContent">
    <param name="movie" value="movie.swf" />
    <!--[if !IE]>-->
    <object type="application/x-shockwave-flash" data="movie.swf" width="480" height="270">
    <!--<![endif]-->
        <ol>
            <li><img src="frame1.jpg" alt="" />It's night-time, a UFO flies over the pasture, cows grazing</li>
            <li><img src="frame2.jpg" alt="" />The UFO tries to abduct two cows using a tractorbeam, however the cows appear to be too heavy to be lifted off the ground</li>
            <li><img src="frame3.jpg" alt="" />It's daytime again, cows are still grazing, one cow looks very relieved</li>
        </ol>
    <!--[if !IE]>-->
    </object>
    <!--<![endif]-->
</object>

和成对使用。它们就像if (!isIE){ //... }。这意味着 IE 将忽略该对内的代码（注意 ! 表示“不”）。它们实际上与 Flash 检测无关。

Flash 检测（实际上是优雅降级）是通过使用以下特性来完成的：当插件不存在时，其对象/嵌入标记将被忽略，并且将显示这些标记内的 HTML。

如果 Flash 不存在，则对于第一个，。对于第二个来说，就是

<ol>
    <li><img src="frame1.jpg" alt="" />It's night-time, a UFO flies over the pasture, cows grazing</li>
    <li><img src="frame2.jpg" alt="" />The UFO tries to abduct two cows using a tractorbeam, however the cows appear to be too heavy to be lifted off the ground</li>
    <li><img src="frame3.jpg" alt="" />It's daytime again, cows are still grazing, one cow looks very relieved</li>
</ol>

No! The code doesn't mean it only check IE.

There are two example in the zip, first one is

<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="728" height="90" id="myFlashContent">
    <param name="movie" value="banner.swf" />
    <!--[if !IE]>-->
    <object type="application/x-shockwave-flash" data="banner.swf" width="728" height="90">
    <!--<![endif]-->
        <img src="banner.jpg" alt="Alternative content rules!" />
    <!--[if !IE]>-->
    </object>
    <!--<![endif]-->
</object>

second one is:

<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="480" height="270" id="myFlashContent">
    <param name="movie" value="movie.swf" />
    <!--[if !IE]>-->
    <object type="application/x-shockwave-flash" data="movie.swf" width="480" height="270">
    <!--<![endif]-->
        <ol>
            <li><img src="frame1.jpg" alt="" />It's night-time, a UFO flies over the pasture, cows grazing</li>
            <li><img src="frame2.jpg" alt="" />The UFO tries to abduct two cows using a tractorbeam, however the cows appear to be too heavy to be lifted off the ground</li>
            <li><img src="frame3.jpg" alt="" />It's daytime again, cows are still grazing, one cow looks very relieved</li>
        </ol>
    <!--[if !IE]>-->
    </object>
    <!--<![endif]-->
</object>

 and  works as a pair. They are just like if (!isIE){ //... }. And what it means is IE will ignore the code inside the pair (pay attention to the ! which means "not"). They are actually not related to Flash detection.

Flash detection(in fact it's graceful degradation) is done by using the characteristic that when the plug-in is not present, its object/embed tag will be ignored and the HTML inside those tags will be displayed.

If Flash is not present, for the first one, <img src="banner.jpg" alt="Alternative content rules!" /> will be displayed. For the second, it's

<ol>
    <li><img src="frame1.jpg" alt="" />It's night-time, a UFO flies over the pasture, cows grazing</li>
    <li><img src="frame2.jpg" alt="" />The UFO tries to abduct two cows using a tractorbeam, however the cows appear to be too heavy to be lifted off the ground</li>
    <li><img src="frame3.jpg" alt="" />It's daytime again, cows are still grazing, one cow looks very relieved</li>
</ol>

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