Regex multiple matching with exec via http://stackoverflow.com/a/2295943/2668831

regex_multi_match.js

myre = /]\(/g
mystr = 'hello ]( world ]( i ]( said ]('

while ((match = myre.exec(mystr)) != null) {
  console.log(myre.lastIndex)
}
/*
8
17
22
30
*/

while ((match = myre.exec(mystr)) != null) {
  console.log(match.index + match[0].length)
}
/*
8
17
22
30
*/

// mystr.length
// 30

/* Note that if assigning a value, repeated overwriting lets you use the last output of the loop
     - can be handy, e.g. find the definitive separator in a markdown link:                       */

var mylink = "![hello ]( world ]( i ]( said ](https://gist.github.com)"

// strip off ![ and ), so start from character 2 and end 3 characters shorter than length
var link_inner = mylink.substr(2, mylink.length - 3);

while ((match = myre.exec(link_inner)) != null) {
  var link_sep = myre.lastIndex;
}

matchstring = '](' // for reference

var link_alt = link_inner.substring(0, link_sep - matchstring.length);
// "hello ]( world ]( i ]( said "
var link_href = link_inner.substring(link_sep);
// "https://gist.github.com"