javascript 中的正则表达式先行问题
我尝试仅在所有空格分隔的单词长度超过 3 个单词字符时进行匹配（3 个单词字符是强制性的，abc* 是正确的，但 ab* 不是）。这是我的测试：
<html>
<body>
<script>
var re = /(?!(\W|^)\w{0,2}(\W|$)).*/i;
var texts = new Array("ab","ab*","abc de*", "ab* def");
for (textindex in texts)
{
var text = texts[textindex];
var matched = re.test(text);
document.write(matched + "<br/>")
}
</script>
</body>
</html>
所有文本都匹配，但我相信没有一个应该匹配。也许我误解了前瞻工作原理的一些基本原理。
I'm trying to match only when all space-separated words are longer than 3 word characters (3 word characters are mandatory, abc* is right but ab* is not). This is my test:
<html>
<body>
<script>
var re = /(?!(\W|^)\w{0,2}(\W|$)).*/i;
var texts = new Array("ab","ab*","abc de*", "ab* def");
for (textindex in texts)
{
var text = texts[textindex];
var matched = re.test(text);
document.write(matched + "<br/>")
}
</script>
</body>
</html>
All texts match, but I believe that none should match. Maybe I'm misunderstanding some fundamental on how lookahead works.
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测试的简单正则表达式是：
至于为什么你的正则表达式不起作用，你的负向前瞻只是意味着“在这个确切的点上不存在”，所以无论你的输入是什么，你都会得到一个匹配至少在该行的末尾。
The simple regex to test that would be:
As for why your regex isn't working, your negative look-ahead simply means "this does not exist at this exact point", so no matter what your input is you'll get a match at the end of the line at the very least.