interpolation function for javascript. Converts strings like "{0}" to substituted values.

interpolation.js

function interpolate(str){
    /* Interpolate on {[0-9]+} */
    if (arguments.length < 2)
      return str;

    /* Break string by it's interpolation parts */
    var split = str.split(/\{([0-9]+)\}/gm);
    var numex = /^\d+$/
    for (var i = split.length - 1; i >= 0; i--) {
      if(numex.test(split[i])){
        var idx = parseInt(split[i]);
        if(arguments.length > idx +1){
          /* Within interpolation bounds */
          split[i] = arguments[idx+1];
        }
      }
    };
    return split.join(" ");
  }