您可以使用 RegExp #exec 方法多次：

You can use the RegExp#exec method several times:

var regex = /a/g;
var str = "abcdab";

var result = [];
var match;
while (match = regex.exec(str))
   result.push(match.index);

alert(result);  // => [0, 4]

助手功能：

function getMatchIndices(regex, str) {
   var result = [];
   var match;
   regex = new RegExp(regex);
   while (match = regex.exec(str))
      result.push(match.index);
   return result;
}

alert(getMatchIndices(/a/g, "abcdab"));