Can't get number based javascript regex pattern to work

Question

I know it should be simple, and yes i've tested on online regex sites, but i just can't get this to work.

Input string: "w_(number from 1-99),h_(number from 1-99)", e.g: "w_34,h_34"

Expected Output: number replaced, e.g "w_50,h_50"

Test:

'w_34,h_34'.replace('w_[1-9][0-9],h_[1-9][0-9]', 'w_50,h_50')

But it just returns the original string. (w_34,h_34)

Gabriel · Accepted Answer · 2013-10-11 22:34:04Z

6

You need to use a regular expression to take advantage of the regexp syntax

'w_34,h_34'.replace(/w_[1-9][0-9]?,h_[1-9][0-9]?/, 'w_50,h_50')

This will solve to only 2 digits of numbers. An alternative would be to use the * operator.

'w_34,h_34'.replace(/w_[1-9][0-9]*,h_[1-9][0-9]*/, 'w_50,h_50')

Which would allow n-length numbers to match.

edited Oct 11, 2013 at 22:34

answered Oct 10, 2013 at 0:33

Gabriel

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4 Comments

Phil Over a year ago

A more flexible number match would be [1-9][0-9]*. Handles anything from 1 onwards

Gabriel Over a year ago

@Phil I opted to use the ? optional operator instead of the * 0 or more.

Phil Over a year ago

@Gabriel But that limits you to numbers between 1 and 99

Gabriel Over a year ago

@Phil yeah I know. It seemed in line with the OP's intentions, though there is technically very little difference in performance. I will add the other alternative and explain the diff in the answer.

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