Regex match expression works in php but not with javascript

Question

I have this string:

$str = "35x35";

The regex function works fine in php, returns true:

preg_match('/^\d*(x|X){1}\d*$/',trim($str))

But when I transfer this function to javascript it doesn't work and it returns null:

$str.trim().match('/^\d*(x|X){1}\d*$/');

What's the problem?

You can explore this: https://stackoverflow.com/questions/34134741/what-is-the-difference-between-php-regex-and-javascript-regex — dkb, Jun 04 '18 at 06:24

score 2 · Accepted Answer · answered Jun 04 '18 at 06:24

2

Remove those '. In Javascript, regex literals are / not '.

const $str = "35x35";

console.log($str.trim().match(/^\d*(x|X){1}\d*$/));

answered Jun 04 '18 at 06:24

Matus Dubrava

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score 0 · Answer 2 · answered Jun 04 '18 at 06:24

0

Here is one solution:

var reg = /^\d*(x|X){1}\d*$/;
var isMatch = reg.test('35x35'); // return true or false

answered Jun 04 '18 at 06:24

Terry Wei

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The fourth bird · Answer 3 · 2018-06-04T06:48:30.560

You can omit {1} from your regex and if you don't use the capturing group (x|X) you could write that as [xX] or just x with the case insensitive flag /i.

Your regex could look like \d+x\d+$ using the and if your want to return a boolean you can use test.

Note that you don't use the single quotes for let pattern and if you use \d* that would match zero or more digits and would also match a single x.

let str = "35x35";
let pattern = /^\d+x\d+$/i;
console.log(pattern.test(str));

Or use match to retrieve the matches.

let str = "35x35";
let pattern = /^\d+x\d+$/i;
console.log(str.match(pattern)[0]);

Regex match expression works in php but not with javascript

3 Answers3