Create Array from Generator in JavaScript

Question

I want to create an array from the values of an generator in JavaScript. The generator creates a sequence of dynamic length like this

function* sequenceGenerator(minVal, maxVal) {
    let currVal = minVal;

    while(currVal < maxVal)
        yield currVal++;
}

I want to store those values in an array but using next() until the generator is done does not seem to be the best way possible (and looks quite ugly to be honest).

var it, curr, arr;

it = sequenceGenerator(100, 1000);
curr = it.next();
arr = [];

while(! curr.done){
    arr.push(curr.value);
}

Can I somehow create an array directly from/within the generator? If not, can I somehow avoid/hide the loop? Maybe by using map or something like that?

Thanks in advance.

philipp · Accepted Answer · 2016-08-11 15:31:58Z

66

One short solution might be:

let list = [...sequenceGenerator(min, max)]

Documentation on MDN

edited Aug 11, 2016 at 15:31

answered Aug 11, 2016 at 15:22

philipp

16.6k15 gold badges66 silver badges121 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Tim Hallyburton · Accepted Answer · 2016-08-11 17:48:12Z

39

I found another way

var arr = Array.from( sequenceGenerator(min, max) );

works aswell.

answered Aug 11, 2016 at 17:48

Tim Hallyburton

2,9891 gold badge25 silver badges30 bronze badges

1 Comment

Eugene Dec 16, 2024 at 4:37

Interesting, why was this accepted instead of simpler one and the one, that had more votes. I thought, that idea, is to mark best answer as the accepted one, not just provde own and accept it.

Redu · Accepted Answer · 2016-08-11 15:25:06Z

4

You can do it like this;

function* sequenceGenerator() {
  let currVal = this.minVal;
  while(currVal <= this.maxVal) yield currVal++;
}
var obj = {minVal: 10, maxVal:20},
    arr;
obj[Symbol.iterator] = sequenceGenerator;
arr = [...obj];
console.log(arr);

answered Aug 11, 2016 at 15:25

Redu

26.3k6 gold badges61 silver badges84 bronze badges

Comments

trincot · Accepted Answer · 2025-02-23 07:00:04Z

0

And yet another way (since ECMAScript 2025):

const arr = sequenceGenerator(min, max).toArray();

function* sequenceGenerator(start, stop) {
    for (let val = start; val < stop; val++) yield val;
}

console.log(sequenceGenerator(2,5).toArray()); // [2, 3, 4]

answered Feb 23 at 7:00

trincot

357k38 gold badges282 silver badges338 bronze badges

Comments

dr0p17 · Accepted Answer · 2024-01-03 07:01:18Z

-1

{let
  isGen = (genProto => (val => genProto.isPrototypeOf(val)))(
    Object.getPrototypeOf(function*(){}) ),
  iterMthdGen = (() => (function() { return this(); })),
  createAddIterMthdFn = (iterMthdFn => ((obj) =>
    Object.assign(obj, {[Symbol.iterator]: iterMthdFn(), }) )),
  addIterMthdGen = createAddIterMthdFn(iterMthdGen),
  wrapGen = (gen => ({[Symbol.iterator]: gen}))
  g = function*() { for(i = 0; i < 10; i++) yield i; };
// [0, 1, 2, 3, 4, 5, 6, 7, 8 , 9],  [0, 1, 2, 3, 4, 5, 6, 7, 8 , 9]
console.log([...wrapGen(g)], [...addIterMthdGen(g)]); }

Using this recipes to work with generators. wrapGen is simpliest method. addIterMthdGen makes generator also an iterable.

answered Jan 3, 2024 at 7:01

dr0p17

1

1 Comment

Community Over a year ago

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.

Collectives™ on Stack Overflow

Create Array from Generator in JavaScript

5 Answers 5

Comments

1 Comment

Comments

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

1 Comment

Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related