gistfile1.js

/*

'My name is #{name=Earl}'.interpolate2(); // "My name is Earl"
'My name is #{name}'.interpolate2({ name: 'Earl2D2' }); // "My name is Earl2D2"

*/
String.prototype.interpolate2 = (function(){
  var re = /#{([-\w]+)(?:=([-\w]+))?}/g;
  return function(source) {
    if (!source) source = { };
    return this.replace(re, function(match, name, value) {
      return (name in source ? source[name] : (value || ''));
    })
  }
})();