HTML脚本标签的位置? [英] HTML script tag placement?
问题描述
每隔一段时间，我就会听到有关稍后将HTML < script> 标记放置在HTML文档中而不是在< head> 元素中的消息.
Every once in a while I hear about placing HTML <script> tags later in the HTML document rather than in the <head> element.
大约有人听说过，甚至提倡将自己的脚本放在</body> 之前的最后几个标签中.
Some people, or so I've heard, even advocate placing one's scripts as the last few tags before </body>.
这是由于性能问题引起的吗?考虑到脚本相关脚本被放置在其他脚本之后，也许加载脚本是一项阻塞的IO操作:
Is this due to a performance issue? Perhaps loading up a script is a blocking IO operation, considering that script-dependent scripts are placed after other scripts like so:
<script src="jQuery.js"></script>
<script src="myScriptThatUsesjQuery.js"></script>
即使是这样，为什么将自己的脚本放在HTML文档的末尾也有帮助呢?
Even if that's the case, why would placing one's scripts near the end of the HTML document help?
谢谢！
推荐答案
当< script> 标签出现在< body> 中时，它会暂停解析文档，直到它被加载(如果适用)并执行为止.这样一来，使用 document.write 的旧脚本就可以发挥作用.
When a <script> tags appears within <body>, it pauses parsing of the document until it's been loaded (if applicable) and executed. This is so that old scripts which use document.write can do their thing.
将< script> 标签放置在主体的最后，以防止它们支撑住东西.
Placing <script> tags last in the body keeps them from holding things up.
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