我正在使用 CodeMirror 并尝试创建我自己的 模式更改演示。我有一个
所以我只需要一种非常粗略/黑客的方式来检测
<mfrac>
<msup>
<msub>
<msqrt>
<mroot>
<mfenced>
<msubsup>
<munderover>
<munder>
<mtable>
<mtr>
<mtd>
<mrow>
<mi>
<mo>
我需要从
I'm using CodeMirror and trying to create my own version of the mode-changing demo. I have a <textarea> on which I listen for changes and when there is a change, I want to look at the value in the <textarea> and determine if it is in the form of MathML.
So I just need to a very crude/hackish way to detect if the value in the <textarea> is MathML; it doesn't have to be perfect. I'm thinking that I can run a regex when the <textarea> changes and look for any of the following tags:
<mfrac>
<msup>
<msub>
<msqrt>
<mroot>
<mfenced>
<msubsup>
<munderover>
<munder>
<mtable>
<mtr>
<mtd>
<mrow>
<mi>
<mo>
I need to take the string from the <textarea> and look if any of these tags are a substring. How would I write this regex?
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将识别任何此类标签的开始。
要找到完整的格式良好的标签，您需要在结束
>之前查找属性，这比较困难。类似的东西不能保证匹配整个标签，但会确保标签开头后有一个
>。编辑：
正则表达式必须位于
/.../内部，就像字符串必须位于引号内一样，因为 JavaScript 解释器就是这样区分正则表达式文字和字符串、数字或任何其他内容的一种令牌。(?:和)形成非捕获组。它与算术表达式中的括号相同。同样的，你必须在(a + b) * (c + d)中使用括号，我在上面使用括号来区分" 和 。 "sup"，前面不带末尾的 匹配
\b是一个分词符。它说名称后面不应该有另一个单词字符。因此" 但不匹配 "。 [^>]*位匹配除'>'之外的任意数量的字符。[...]是一个字符集，因此[az]匹配任何小写罗马字母。^对其取反，因此[^az]匹配任何非小写罗马字母的字符。will identify the start of any such tag.
To find a whole well-formed tag, you need to look for attributes before the closing
>which is tougher. Something likeis not guaranteed to match a whole tag, but will make sure there is a
>after the start of the tag.EDIT:
The regular expression has to be inside
/.../the same way a string has to be inside quotes because that is how the JavaScript interpreter tells a regular expression literal from a string or a number or any other kind of token.The
<mmatches the first two characters of any mathml tag. The(?:and)form a non-capturing group. It's the same as parentheses in an arithmetic expression. In the same way you have to use parentheses in(a + b) * (c + d)I use parentheses above to distinguish<m(?:frac|sup)from<mfrac|sup. The latter would match both"<mfrac"and"sup"without a<mbefore it.The
\bat the end is a word break. It says that there shouldn't be another word character after the name. So<msub\bmatches"<msub"but not"<msubmarine".The
[^>]*bit matches any number of characters other than'>'. The[...]is a character set, so[a-z]matches any lower-case roman letter. The^negates it, so[^a-z]matches any character that is not a lower-case roman letter.