// Function to look for all matches

var execAll = function(regex, string) {

    var match = null;

    var matches = new Array();

    while (match = regex.exec(string)) {

        var matchArray = [];

        for (i in match) {

            if (parseInt(i) == i) {

                matchArray.push(match[i]);

            }

        }

        matches.push(matchArray);

    }

    return matches;

};

​

// Instagram regex, slightly modifed with a /g

var reg = /(?:@)([A-Za-z0-9_](?:(?:[A-Za-z0-9_]|(?:\.(?!\.))){0,28}(?:[A-Za-z0-9_]))?)/g;

​

var sentance = "this is a @sample.user@user2 and @other.user_ we want.";

​

var answer = execAll(reg, sentance);

​

console.log(answer);