CODEWITHSUNDEEP
typescript
Michael
Michael

Reputation: 375

How do I solve the "a Element implicitly has an 'any' type because index expression is not of type 'number'" error?

I'm using Typescript with strict compiler options which I really like. But when I have a for loop I get the following error a Element implicitly has an 'any' type because index expression is not of type 'number'. I changed let i to let i:number shouldn't that fix it?

Here is the

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Upvotes: 1

Views: 8842

Answers (2)

Xyrue
Xyrue

Reputation: 81

This error has nothing to do with your i variable. event.touches's type is TouchList, this is how it looks:

interface TouchList {
    readonly length: number;
    item(index: number): Touch | null;
    [index: number]: Touch;
}

The index has to be a number yet Object.keys returns a string[] and this is why you have a type mismatch.

You need to cast the string to number. You can do something as simple as Number(keys[i]) but there are at least two keys (length & item) that are not numbers so I recommend that you check that your casting returns an actual number first and only then push it to this.touches

Upvotes: 0

MEDZ
MEDZ

Reputation: 2295

You can cast the value of keys[i]:

this.touches.push(event.touches[(keys[i] as number)])

Or if you expect it to be string then (keys[i] as string)

Upvotes: 1

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