Array in array, I get an error: Type '[string, string, number]' is not assignable to type '[]'

Question

I want to have an array full of other array that contain string or numbers:

var mainarray: [] = [];
xy.forEach(function (foo) {
    var subarray: [] = ['test', 'test', 3];
    mainarray.push(subarray);
});

However I get this errors:

 Type '[string, string, number]' is not assignable to type '[]'.
Argument of type '[]' is not assignable to parameter of type 'never'.

How do I have to declare the variable mainarray and subarray so that this works?

(Later I use this array to create a jsonstring)

With orders.push(subarray); you mean mainarray.push(subarray); ?? — Ashish Ranjan
– Ashish Ranjan, Commented Jan 5, 2019 at 15:59

Ashish Ranjan · Accepted Answer · 2019-01-05 15:48:51Z

3

Give the type of your array as:

var mainarray: Array<number | string>[] = [];

answered Jan 5, 2019 at 15:48

Ashish Ranjan

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3 Comments

nbar Over a year ago

Only the subarray has number or string in it, the mainarray has subarrays in it. So would it be something like this: var mainarray: Array<Array<number | string>[]>[] = []; This looks kinda confusing

Hero Wanders Over a year ago

Notice that for each type T the following are equivalent types: Array<T> and T[]. Alternative notations for the solution @xyz has given: Array<(number | string)[]>, Array<Array<number | string>> or (number | string)[][]

Ashish Ranjan Over a year ago

@nbar: No, I think a single Array<number | string> should do. It says that the content of mainarray is of type array which in itself can contain numbers or strings. Is it not working?

ye-olde-dev · Accepted Answer · 2019-01-05 15:55:14Z

0

not quite sure what you're trying to accomplish here, so I can't provide a better answer without context, but you can do it like this:

let mainarray = [];
let xy = [1,2];

function test() {
     xy.forEach(x => {
         mainarray = [ ...mainarray, ['test', 'test', 3]];
     })

    console.log(mainarray);
}

answered Jan 5, 2019 at 15:55

ye-olde-dev

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Comments

Unknown · Accepted Answer · 2019-01-05 16:01:00Z

0

I got another error message, while trying to run this code snippet:

Type '[string, string, number]' is not assignable to type '[]'. Types of property 'length' are incompatible. Type '3' is not assignable to type '0'.

So your type declaration should be string[] |number[] or (string | number)[] and not just []. Consequently your code snippet should look like this:

var mainarray: [] = [];
xy.forEach(function (foo) {
    var subarray: string[] | number[] = ['test', 'test', 3];
    orders.push(subarray);
});

answered Jan 5, 2019 at 16:01

Unknown

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