Function keyOf

lib/web/polyfill.js:208–215

(object, el)

  return T;
};
function keyOf(object, el){
  var O      = toObject(object)
    , keys   = getKeys(O)
    , length = keys.length
    , index  = 0
    , key;
  while(length > index)if(O[key = keys[index++]] === el)return key;
}

// Array
// array('str1,str2,str3') => ['str1', 'str2', 'str3']