How do I assign type when using forEach in Typescript(Object of type unknown)

Question

let payload = {
  item1: ["value1", "value2", "value3"],
  item2: [],
  item3: ["value4", "value5"]
}

Object.entries(payload).forEach(([key, values]) => {
if (values.length === 0) {
    // do this stuff

I'm getting an error that values is of type unknown. I'm not sure how to give it a type of array.

key will always be a string, and values will always be an array of strings.

interface Payload { item1: any; item2: any; item3: any } then, payload: Payload [] — Thilina Koggalage
– Thilina Koggalage, Commented Nov 15, 2019 at 5:02
Ah ok that makes sense. The items I get is random since its from an API call, how do i not hardcode it to 3 items? and I would just put string[] for an array of strings? — Mr. Teddy
– Mr. Teddy, Commented Nov 15, 2019 at 5:13

MjZac · Accepted Answer · 2019-11-15 05:34:47Z

3

You can specify type of the key in an interface, so you wont be limited to a number.

interface Payload{
    [key: string]: string[];
}

const payload: Payload = {
    a: ['foo', 'bar'],
    b: [],
    c: ['baz']
};
Object.keys(payload).forEach((key, idx) => {
    if (payload[key].length === 0) {
    // do the stuff
}
});

Here's link to playground

answered Nov 15, 2019 at 5:34

MjZac

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1 Comment

Mr. Teddy Over a year ago

Awesome thanks! I have to parse the payload, but I guess having a 2nd variable isn't too dirty. Will use this

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