Nodejs Array First or Null firstOrNull(predicate)

Method Source Code

/*//from  w w w . ja  va 2 s .c om
   Extensions to Javascript Objects.
*/


/**
 * Returns the first element that respects an arbitrary predicate, or null if it doesn't finds one.
 */
Array.prototype.firstOrNull = function(predicate){
   var tmp = this.filter(
            (function(){
               // Set to false as soon as it finds a matching item
               var first = true;

               //Return function with closured var first
               return function(item){
                  // If already found one elem, stops testing conds and returns always false
                  if(!first) return false;

                  // If doesn't have an item yet, test conds; return true as soon as it finds one
                  if(predicate(item)){
                     first = false;
                     return true;
                  }

                  // returns false if all fails
                  return false;
               }
            })());
   //---

   return tmp && tmp[0] ? tmp[0] : null;
}

Array.prototype.contains = function(item){
   return this.indexOf(item) > -1;
}

Related

1. firstOrNull()

   Array.prototype.firstOrNull = function () {
     if (this.length > 0) {
       return this[0];
     return null;