CODEWITHSUNDEEP
javascript
dev
dev

Reputation: 916

adding dynamic values to regex

I am having a regex where i check the input is having 6 digit number. I am able to achieve it with the below refgex

/^\d{6}$/gm.test("123456")

I have used this regex in multiple places so I am trying to make it as a function

function testNumber(number, digitLength = 6){
  return /^\d{6}$/gm.test(number)
}

Now in some places the digitLength is of 3 and in some places its 4, now how can i interpolate the digitLength in the regex so i can pass as much the digitLength instead of hardcoding 6 in the regex.

Any help is appreciated

Upvotes: 2

Views: 2437

Answers (2)

Xeelley
Xeelley

Reputation: 1116

You are looking for (your regex):

function testNumber(number, digitLength = 6){
  return new RegExp(`^\\d{${digitLength}}$`, 'gm').test(number);
}

Refs: RegExp, Template literals.

Same, but optimized:
As @Thomas noticed, you don't need g flag in your case, because you always match global (full string), and you don't need m flag too, because you accept one-line inputs. So regex like this is enough:

function testNumber(number, digitLength = 6){
  return new RegExp(`^\\d{${digitLength}}$`).test(number);
}

Upvotes: 2

Thomas
Thomas

Reputation: 12637

Instead of a dynamic regex you could also do it like this:

function testNumber(number, digitLength = 6){
  return number.length === digitLength // check expected length
    && /^\d+$/.test(number);           // and that it is all digits
}

Upvotes: 2

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