It might be simple question, but I have not figured out as I am still newbie in TypeScript, I have a variable:
let v1: number | number[];
I want to convert
let v2: number[];
If v1 = 1 => v2 will be [1]
if v1= [1, 2] => v2 will be [1,2]
Test if the variable is an array, create one if not:
const v2 = Array.isArray(v1) ? v1 : [v1];
Accepted answer seems to have minor side effect (when v1 is array, v2 will inherit reference to v1):
const v1: number | number[] = [1, 2]
const v2: number[] = Array.isArray(v1) ? v1 : [v1] // v1: [1, 2], v2: [1, 2]
v1.push(3) // v1: [1, 2, 3], v2: [1, 2, 3]
I may suggest my solution (simply use Array.prototype.concat()):
let v1: number | number[]
let v2: number[]
v1 = 1
v2 = Array().concat(v1) // v2: [1]
v1 = [1, 2]
v2 = Array().concat(v1) // v2: [1, 2]