javascript RegExp.test 不工作？
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RegExp.test not working?
提问by user424134
I am trying to validate year using Regex.test in javascript, but no able to figure out why its returning false.
我试图在 javascript 中使用 Regex.test 验证年份，但无法弄清楚为什么它返回 false。
var regEx = new RegExp("^(19|20)[\d]{2,2}$");
regEx.test(inputValue)returns false for input value 1981, 2007
regEx.test(inputValue)为输入值 1981, 2007 返回 false
Thanks
谢谢
回答by BoltClock
As you're creating a RegExpobject using a string expression, you need to double the backslashes so they escape properly. Also [\d]{2,2}can simply be condensed to \d\d:
当您RegExp使用字符串表达式创建对象时，您需要将反斜杠加倍，以便它们正确转义。也[\d]{2,2}可以简单地浓缩为\d\d：
var regEx = new RegExp("^(19|20)\d\d$");
Or better yet use a regex literal to avoid doubling backslashes:
或者更好的是使用正则表达式来避免双反斜杠：
var regEx = /^(19|20)\d\d$/;
回答by Mrchief
Found the REALissue:
发现真正的问题：
Change your declaration to remove quotes:
更改您的声明以删除引号：
var regEx = new RegExp(/^(19|20)[\d]{2,2}$/);
回答by Mike C
Do you mean
你的意思是
var inputValue = "1981, 2007";
If so, this will fail because the pattern is not matched due to the start string (^) and end string ($) characters.
如果是这样，这将失败，因为由于开始字符串 (^) 和结束字符串 ($) 字符导致模式不匹配。
If you want to capture both years, remove these characters from your pattern and do a global match (with /g)
如果您想捕获这两年，请从您的模式中删除这些字符并进行全局匹配（使用 /g）
var regEx = new RegExp(/(?:19|20)\d{2}/g);
var inputValue = "1981, 2007";
var matches = inputValue.match(regEx);
matches will be an array containing all matches.
匹配将是一个包含所有匹配项的数组。
回答by Luke
I've noticed, for reasons I can't explain, sometimes you have to have two \\ in front of the d.
我注意到，出于我无法解释的原因，有时您必须在 d 前面有两个 \\。
so try [\\d] and see if that helps.
所以尝试 [\\d] 看看是否有帮助。
