How to find right regex for date?

Question

I have a date like this: "2019" and i want to find a regex for it in javascript. my code return false at all. can you help me please ?

let regex = new RegExp('\d{4}');
if regex.test("2019"){
    console.log("true");
} else {
    console.log("false");
}

Tim Biegeleisen · Accepted Answer · 2019-07-29 05:11:54Z

2

The immediate error in your syntax is that your are using RegExp, in which you would need to double escape \\d{4} your pattern. So new RegExp('\\d{4}') should work.

Your regex logic seems OK, but I would recommend that you always use the native regex syntax if possible:

var input = "2019";
if (/^\d{4}$/.test(input)) {
    console.log("true");
}
else {
    console.log("false");
}

An exception for using RegExp with its string constructor would be a situation where you had to build a regex pattern by piecing together other strings. In this case, you might have to use RegExp.

answered Jul 29, 2019 at 5:11

Tim Biegeleisen

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