Question

I’m experimenting with functional-style Javascript and have encountered an interesting situation. I have a foreach function that takes a collection and function object:

var Utils = {};

// Applies a functor to each item in a collection.
Utils.foreach = function(collection, functor)
{
  for (var i = 0; i < collection.length; i++)
  {
    functor(collection[i]);
  }
};

This is cool. However now I want to implement another function:

// Checks if a collection contains an item.
Utils.has = function(collection, item)
{
    Utils.foreach(collection, function(obj) {
        if (item === obj) {
            return true; // How to force a return from the foreach function?
        }
    });
    return false;
};

As you can see I can’t implement the “has” function because my return statement doesn’t break the iteration.

Can someone recommend a solution for this problem?

Answer 1

I guess what you want is not actually forEach, but rather some (other languages call it any). The couterpart is every (or all in other languages). You’ll find an example implementation on MDC.