Regular Expresion indexOf for Arrays

reIndexOf.js

/**
 * Regular Expresion IndexOf for Arrays
 *   This little addition to the Array prototype will iterate over array
 *   and return the index of the first element which matches the provided
 *   regular expresion. Note: This will not match on objects.
 * @param  {RegEx}   rx The regular expression to test with. E.g. /-ba/gim
 * @return {Numeric} -1 means not found
 */
if (typeof Array.prototype.reIndexOf === 'undefined') {
  Array.prototype.reIndexOf = function (str) {
    for (var i in this) {
      if (str.toString().match(this[i])) {
        return i;
      }
    }
    return -1;
  };
}

I stopped attaching this to the Array construct.
I now use this as a function rewritten such as the alternate below.

---

The following alternate-form that lets you pass in strings which become caseInsensitive / globally searched Regular Expressions:

function reIndexOf(array, str) {
  if (str) {
    for (var i in array) {
      if (str.toString().match(new RegExp(array[i], 'ig'))) {
        return i;
      }
    }
  }
  return -1;
}

Used such as:

var a = [ 'rocks', 'box', 'fox' ];

reIndexOf(a, 'Arctic foxes are common throughout Northern tundra biomes.')

Outputs: 2