dynamically generate array using .forEach()

Question

In python, you can do:

ints = [1, 2, 3]
str_ints = [str(my_int) for my_int in ints]
print(str_ints)

which outputs:

['1', '2', '3']

I want to do something similar using javascript using forEach,

let ints = [1, 2, 3]
str_ints = [ints.forEach(my_int => {return String(my_int)})]
console.log(str_ints)

I would expect the output to be:

Array ['1', '2', '3']

however, the output is

Array[undefined]

Is this sort of array creation not possible in javascript?

Why do you want to use forEach instead of functionality designed for the task you want? — VLAZ
– VLAZ, Commented May 12, 2019 at 21:37
Another way to simulate array comprehension in JS - stackoverflow.com/questions/45310911/… — Ori Drori
– Ori Drori, Commented May 12, 2019 at 21:40

Ori Drori · Accepted Answer · 2019-05-12 21:38:57Z

4

That's called mapping, and here's how you do it in JavaScript:

var ints = [1, 2, 3];
var str_ints = ints.map((i) => String(i));
console.log(str_ints);

As suggested by @OriDrori, you can omit the arrow function:

var ints = [1, 2, 3];
var str_ints = ints.map(String);
console.log(str_ints);

Ori Drori

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answered May 12, 2019 at 21:36

Djaouad

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