Get all substrings inside a string that match a regular expression

Possible Duplicate:
How can I match multiple occurrences with a regex in JavaScript similar to PHP's preg_match_all()?

In Javascript, is it possible to find the starting and ending indices of all substrings within a string that match a regular expression?

Function signature:

function getMatches(theString, theRegex){
    //return the starting and ending indices of match of theRegex inside theString
    //a 2D array should be returned
}

For example:

getMatches("cats and rats", /(c|r)ats/);

should return the array [[0, 3], [9, 12]], which represents the starting and ending indices of "cats" and "rats" within the string.