safer string formatting

string.format.js

// Inspired by http://bit.ly/juSAWl
// Augment String.prototype to allow for easier formatting.  This implementation 
// doesn't completely destroy any existing String.prototype.format functions,
// and will stringify objects/arrays.
String.prototype.format = function(i, safe, arg) {

  function format() {
    var str = this, len = arguments.length+1;

    // For each {0} {1} {n...} replace with the argument in that position.  If 
    // the argument is an object or an array it will be stringified to JSON.
    for (i=0; i < len; arg = arguments[i++]) {
      safe = typeof arg === 'object' ? JSON.stringify(arg) : arg;
      str = str.replace(RegExp('\\{'+(i-1)+'\\}', 'g'), safe);
    }
    return str;
  }

  // Save a reference of what may already exist under the property native.  
  // Allows for doing something like: if("".format.native) { /* use native */ }
  format.native = String.prototype.format;

  // Replace the prototype property
  return format;

}();

using.js

// include string.format.js

// simple string replacement
console.log(
"{0} is a {1} and likes to {2}".format("Tim", "programmer", "kick potatoes");
); // Tim is a programmer and likes to kick potatoes

// object handling
console.log(
"{0} is my favorite object".format({lol:'hi'})
); // {"lol":"hi"} is my favorite object

// array handling
console.log(
"my array: {0}".format([1,2,3,4,5])
); // my array: [1,2,3,4,5]

// multiple reuse
console.log(
  "{0} is a {0} is a {0}".format("steve jobes")
); // ""steve jobes" is a "steve jobes" is a "steve jobes""

consider using the best option in replaceAll method: http://jsperf.com/replace-all-vs-split-join/25