How can I define types for (const item of entries) in Typescript?

I attempted

for (const ElementType as element of elements ) {}

or

for (const ElementType of elements as element) {}

However, neither of these options is correct.

Answer №1

No action is required on your part.

interface ExampleElement {
    key: integer;
}

const list: TestElement[] = [];

for (const item of list ) {
    item // Automatically converted to ExampleElement type
}

Answer №2

It's interesting that Typescript doesn't support type annotations or assertions on variables within loops like for/of. A workaround to achieve similar functionality is by asserting the type of the array instead of the individual elements:

let arr: any = [1, 2, 3, 4];

for (let x of (arr as number[])) {
    x // number
}

Although it may seem a bit messy with the additional brackets, it gets the job done.

Check out this Playground Link for more details.

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