JavaScript global match group and replace

match-replace.js

var hash = { prop_a: "abc", prop_b: "def", prop_c: "ghi" };

function getMatches (string, regex) {
  var match;
  while (match = regex.exec(string)) {
    var prop = match[1];
    string = string.slice(0, match.index) + hash[prop] + string.slice(match.index + prop.length + 4); 
  }   
  output = string;
}

// Example :
var input = '{{prop_a}} calls {{prop_c}} as {{prop_b}}',
  myRegEx = /{{([^{}]*)}}/,
  output;

getMatches(input, myRegEx); 

console.log(output);