Javascript正则表达式-RegEx对象的字符串 [英] Javascript regular expression - string to RegEx object

问题描述

我确定它确实很小，但是我无法弄清楚.

I am sure its something pretty small that I am missing but I haven't been able to figure it out.

我有一个带有regex模式的JavaScript变量，但我似乎无法使其与RegEx类一起工作

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

以下内容始终为false:

the following always evaluates to false:

var value = "[e-mail]";
var pattern = "^\w+@[a-zA-Z_]+?\.[a-zA-Z]{2,3}$"
var re = new RegExp(pattern);
re.test(value);

但是如果我将其更改为正确的正则表达式(通过删除引号并在模式的开头和结尾添加/)，它将开始工作:

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:

var value = "[e-mail]";
var pattern = /^\w+@[a-zA-Z_]+?\.[a-zA-Z]{2,3}$/
var re = new RegExp(pattern);
re.test(value);

由于我总是将模式作为字符串包含在变量中，所以我一直无法弄清这里缺少的内容.

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.

推荐答案

反斜杠是字符串中的特殊字符，需要用另一个反斜杠转义:

Backslashes are special characters in strings that need to be escaped with another backslash:

var value = "[e-mail]";
var pattern = "^\\w+@[a-zA-Z_]+?\\.[a-zA-Z]{2,3}$"
var re = new RegExp(pattern);
re.test(value);

这篇关于Javascript正则表达式-RegEx对象的字符串的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！