How to create an array containing 1 N

Question

I'm looking for alternatives to the following for creating a JavaScript array with values ranging from 1 to N, where N is only known at 

runtime.

var foo = [];

for (var i = 1; i <= N; i++) {
   foo.push(i);
}

There should be a way to do this without the loop, in my opinion.

Answer 1

Array from() and keys() methods are used in ES6.

Array.from(Array(10).keys())
//=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Shorter version employing the spread operator.

[...Array(10).keys()]
//=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Begin at 1 by supplying the map function to Array from() and passing an object with a length property:

Array.from({length: 10}, (_, i) => i + 1)
//=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]