Array.prototype.indexOf polyfill by aMarCruz

indexOf_polyfill.js

//
// https://msdn.microsoft.com/library/ff679977(v=vs.94).aspx
// https://developer.mozilla.org/es/docs/Web/JavaScript/Referencia/Objetos_globales/Array/indexOf
//
Array.prototype.indexOf || (Array.prototype.indexOf = function (searchElement /*, fromIndex */ ) {
  'use strict';
  
  if (this == null) {
    throw new TypeError();
  }
  
  var t = Object(this);
  var len = t.length | 0;   //to int32
  if (len === 0) {
    return -1;
  }
  
  var n = 0;
  if (arguments.length > 1) {
    n = Number(arguments[1]);
    if (n !== n || !isFinite(n)) { // para verificar si es NaN
      n = 0;
    } else if (n !== 0) {
      n = Math.floor(n);
      if (n < 0) {
        n = Math.max(len - Math.abs(n), 0);
      }
    }
  }

  for (; n < len; n++) {
    if (n in t && t[n] === searchElement) {
      return n;
    }
  }
  return -1;

});