How can I capture multiple groups, multiple times with javascript regex

Question

I have this code snippet aiming to extract next and last link values from github api...

var types = {},
    str = '<https://api.github.com/repositories/1424470/issues?access_token=f554f90b4c95c78091a4202150d4583082dab1ce&page=2>; rel="next", <https://api.github.com/repositories/1424470/issues?access_token=f554f90b4c95c78091a4202150d4583082dab1ce&page=7>; rel="last"',
    rex = /\s*<https?:\/\/api.github.com\/.+?&page=(\d+)>;\s*rel="(\w+?)"(?:,|$)/g;

// use regex replace method to capture multiple groups multiple times
str.replace(rex, function(_, page, type){
    types[type] = +page;
});

console.log(types);
// {next: 2, last: 7}

It is functioning correctly, but feels like a mis-use of regex replace method, where I am not returning anything, but using it only for the sake of having a callback for each match, which I use to build up an output object.

I would prefer some kind of matchAll, returning multi-dimensional array of matches, and parts.

Is there a better way to handle this case in javascript?

@hwnd that looks reasonable. A bit of a pain to have to write out the logic each time. Probably good case for utility function. — Billy Moon
– Billy Moon, Commented Aug 1, 2015 at 23:55
I mean the approach looks good. I had forgotten about regex.exec maintaining a starting index, allowing it to be called repeatedly, which is probably the most reasonable way to do it, but for such a general functionality, I would like to just pass a string and a pattern to a utility function, and be given back a multi-dimensional array of matches. — Billy Moon
– Billy Moon, Commented Aug 2, 2015 at 0:01

hwnd · Accepted Answer · 2015-08-02 00:10:12Z

1

You can use the exec() method in a loop, pushing the match results to a multi-dimensional array.

function find_all(re, s) {
   var types = [];
   while (m = re.exec(s)) {
        types.push([m[2], m[1]])
   }
   return types;
}

var regex = new RegExp('<https?://[^>]+page=(\\d+)>;\\s*rel="([^"]+)"', 'gi');

find_all(regex, str) //=> [ [ 'next', '2' ], [ 'last', '7' ] ]

edited Aug 2, 2015 at 0:10

answered Aug 1, 2015 at 23:55

hwnd

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