Check if Array Contains Item - http://stackoverflow.com/questions/1181575/determine-whether-an-array-contains-a-value

arr-contains-item.js

/**
 * A function to determine if an array contains an item
 * @param needle - [Number||String] - The array to search through
 * @returns [boolean] - Returns true or false
 */
function arrContainsItem(needle) {
  var findNaN = needle !== needle; // Per spec, the way to identify NaN is that it is not equal to itself
  var indexOf;

  if(!findNaN && typeof Array.prototype.indexOf === 'function') {
    indexOf = Array.prototype.indexOf;
  } else {
    indexOf = function(needle) {
      var i = -1, index = -1;

      for(i = 0; i < this.length; i++) {
        var item = this[i];

        if((findNaN && item !== item) || item === needle) {
          index = i;
          break;
        }
      }

      return index;
    };
  }

  return indexOf.call(this, needle) > -1;
}

// Usage
var arrayToCheck = ["string", 24];
console.log(arrContainsItem.call(arrayToCheck, itemToCheckFor));