I want to create 10 Fly objects in a functional manner. I thought this would work:
var flies = new Array(10).map(function() {
return new Fly();
});
It doesn't. It creates an array of length ten with undefined as their values.
How can I create 10 objects without using for(var i = 0; i < 10; i++)...?
EDIT: This is an academic exercise for the sake of learning only. It's find if a for is used under the hood. I'm just trying to figure out what JavaScript can do.
Out of the box, there is only @elcanrs way. If you use a library such as Underscore you could use http://underscorejs.org/#times
var flies = _.times(10, function(){return new Fly()})
_.times uses to do this? Yep! A for: for (var i = 0; i < n; i++) accum[i] = iteratee(i); :-D
for is silly since any other solution will probably just use it internally.
I'm pretty sure that any fancy approach will be using a for, or another loop, at a lower level... If you reeeealy want to get rid of this, you can work with a recursive approach and create your own Fly Factory function!
Honestly, IMO it's a waste of effort. But at least it has not for loop! =D
function Fly() {
}
function CreateFlies(n) {
var arr = [new Fly()];
arr = (n > 1 ? arr.concat(CreateFlies(n-1)) : arr);
return arr;
}
var flies = CreateFlies(10);
alert(flies);
Array.apply(0, Array(10)).mapfor?[0,1,2,3,4,5,6,7,8,9].map- if you're dead set againstforcallback is invoked only for indexes of the array which have assigned values; it is not invoked for indexes that are undefined, those which have been deleted or which have never been assigned values.Array.from({length: 10}, _ => new Fly());