JavaScript：模拟“ foreach”循环中的“ break”

Question

What is the best way to implement a siulation of 'break' feature of a for-loop when you are iterating through an user/engine-defined function?

foreach([0,1,2,3,4],function(n){
    console.log(n);
    if (n==2)
        break;});

I've thought in implementing foreach in a way that would break when the function returned 'false' - but I would like to hear thoughts on how that is normally done.

Answer 1

return ing false is the most common way to do it. That's what jQuery's iterator function .each() does:

We can break the $.each() loop at a particular iteration by making the callback function return false . Returning non-false is the same as a continue statement in a for loop; it will skip immediately to the next iteration.

And its very simplified implementation:

each: function( object, callback ) {
  var i = 0, length = object.length,
  for ( var value = object[0]; 
        i < length && callback.call( value, i, value ) !== false; // break if false is returned by the callback 
        value = object[++i] ) {}
  return object;
}