Google的+1按钮:他们是如何做到的? [英] Google's +1 Button: How do they do it?

问题描述

浏览Google的+1按钮后，我发现它们提供的代码有两点奇怪:

Exploring Google's +1 Button, I found two things odd about the code they supply:

<script type="text/javascript" src="https://apis.google.com/js/plusone.js">
  {lang: 'en-GB'}
</script>

<g:plusone size="tall" href="http://www.google.com"></g:plusone>

所以我有两个问题:
第一:       Google如何使用 script 标记之间的文本?
第二个: 语法< g:plusone ... HTML是否有效?这叫什么?

So I have two questions:
First:       How is Google able to use the text between the script tags?
Second:  Is the syntax <g:plusone ... HTML valid? What's this called?

推荐答案

Google如何使用脚本标记之间的文本?

How is Google able to use the text between the script tags?

< script> 元素在DOM中完全可见:

<script> elements are perfectly visible in the DOM:

<script type="text/javascript">//FIRST SCRIPT BLOCK</script>

<script type="text/javascript">
    var s= document.getElementsByTagName('script')[0];
    alert(s.textContent); // "//FIRST SCRIPT BLOCK"
</script>

Google的偷偷摸摸的技巧是将内容放入具有外部 src 的< script> 中.在这种情况下， src 会覆盖块内的内容并执行外部脚本，但是即使通过DOM仍可以读取< script> 元素的内容他们什么都不做.

Google's sneaky trick is to put content in a <script> that has an external src. In this case the src overrides the content inside the block and executes the external script instead, but the contents of the <script> element are still readable through the DOM even though they do nothing.

语法< g:plusone ... HTML是否有效?这叫什么?

Is the syntax <g:plusone ... HTML valid? What's this called?

不.如果他们为HTML + plusone编写了自己的文档类型，那么它可能是有效的 that ，但是它不能满足HTML的有效性，并且在XHTML文档中它甚至都不是命名空间格式良好的格式，除非您也为此添加了一个额外的 xmlns:g .

No. If they made their own doctype for HTML+plusone it could be valid that, but it doesn't satisfy validity for HTML, and it isn't even namespace-well-formed in an XHTML document, unless you add an extra xmlns:g for it too.

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