Looping with a callback

JavaScript

function loop(array, fn){ 
  for ( var i = 0; i < array.length; i++ ) {
    fn.apply(this, args)
  }
} 
var num = 0; 
loop([0, 1, 2], function(value){ 
  console.log(value == num++); 
  console.log(this instanceof Array);
});