JavaScript 正则表达式异常（无效组）
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JavaScript regular expression exception (Invalid group)
提问by Maksim Vi.
I have the following regular expression:
我有以下正则表达式：
/(?<={index:)\d+(?=})/g
I am trying to find index integer in strings like this one:
我试图在这样的字符串中找到索引整数：
some text{index:1}{id:2}{value:3}
That expression works fine with php, but it doesn't work in javascript, I get the following error:
该表达式适用于 php，但不适用于 javascript，我收到以下错误：
Uncaught SyntaxError: Invalid regular expression: /(?<={index:)\d+(?=})/: Invalid group
Uncaught SyntaxError: Invalid regular expression: /(?<={index:)\d+(?=})/: Invalid group
What do I need to fix?
我需要修复什么？
Thanks.
谢谢。
采纳答案by Phrogz
var str = "some text{index:1}{id:2}{value:3}";
var index = str.match(/{index:(\d+)}/);
index = index && index[1]*1;
回答by mike
(?<= )is a positive lookbehind. JavaScript's flavor of RegEx does not support lookbehinds (but it does support lookaheads).
(?<= )是积极的回顾。JavaScript 的 RegEx 风格不支持lookbehinds（但它支持lookaheads）。
回答by cdhowie
JavaScript does not support look-behind assertions. Use this pattern instead:
JavaScript 不支持后视断言。请改用此模式：
/{index:(\d+)}/g
Then extract the value captured in the group.
然后提取在组中捕获的值。
