Javascript 正则表达式 - 字符串到 RegEx 对象
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Javascript regular expression - string to RegEx object
提问by shake
I am sure its something pretty small that I am missing but I haven't been able to figure it out.
我确信它是我遗漏的很小的东西，但我一直无法弄清楚。
I have a JavaScript variable with the regex pattern in it but I cant seem to be able to make it work with the RegEx class
我有一个带有正则表达式模式的 JavaScript 变量，但我似乎无法使其与 RegEx 类一起使用
the following always evaluates to false:
以下总是评估为假：
var value = "[email protected]";
var pattern = "^\w+@[a-zA-Z_]+?\.[a-zA-Z]{2,3}$"
var re = new RegExp(pattern);
re.test(value);
but if I change it into a proper regex expression (by removing the quotes and adding the /at the start and end of the pattern), it starts working:
但是如果我将其更改为适当的正则表达式（通过删除引号并/在模式的开头和结尾添加），它就会开始工作：
var value = "[email protected]";
var pattern = /^\w+@[a-zA-Z_]+?\.[a-zA-Z]{2,3}$/
var re = new RegExp(pattern);
re.test(value);
since I always get the pattern as a string in a variable, I haven't been able to figure out what I am missing here.
由于我总是将模式作为变量中的字符串获取，因此我无法弄清楚我在这里遗漏了什么。
回答by RoToRa
Backslashes are special characters in strings that need to be escaped with another backslash:
反斜杠是字符串中需要用另一个反斜杠转义的特殊字符：
var value = "[email protected]";
var pattern = "^\w+@[a-zA-Z_]+?\.[a-zA-Z]{2,3}$"
var re = new RegExp(pattern);
re.test(value);
