Short circuit Array.forEach like calling break

You can use every method:

[1,2,3].every(function(el) {

    return !(el === 1);

});

ES6

[1,2,3].every( el => el !== 1 )

for old browser support use:



if (!Array.prototype.every)

{

  Array.prototype.every = function(fun /, thisp/)

  {

    var len = this.length;

    if (typeof fun != "function")

      throw new TypeError();



    var thisp = arguments[1];

    for (var i = 0; i < len; i++)

    {

      if (i in this &&

          !fun.call(thisp, this[i], i, this))

        return false;

    }



    return true;

  };

}

4 years ago

There's no built-in ability to break in forEach. To interrupt execution you would have to throw an exception of some sort. eg.

var BreakException = {};



try {

  [1, 2, 3].forEach(function(el) {

    console.log(el);

    if (el === 2) throw BreakException;

  });

} catch (e) {

  if (e !== BreakException) throw e;

}

JavaScript exceptions aren't terribly pretty. A traditional for loop might be more appropriate if you really need to break inside it.

Use Array#some

[1, 2, 3].some(function(el) {

  console.log(el);

  return el === 2;

});

This works because some returns true as soon as any of the callbacks, executed in array order, return true, short-circuiting the execution of the rest.

some, its inverse every (which will stop on a return false), and forEach are all ECMAScript Fifth Edition methods which will need to be added to the Array.prototype on browsers where they're missing.

4 years ago