CODEWITHSUNDEEP
typescript
Foreign
Foreign

Reputation: 405

How to fix this type inference in Typescript

const data = {
    "a": "111",
    "b": "222"
}

for (let key in data){
    console.log(data[key]); // TypeScript error here
}

Error:

Element implicitly has an 'any' type because expression of type 'string' can't be used to index type '{ "a": string; "b": string; }'. No index signature with a parameter of type 'string' was found on type '{ "a": string; "b": string; }'.

Upvotes: 0

Views: 142

Answers (2)

Alex Wayne
Alex Wayne

Reputation: 186994

You could:

console.log(data[key as keyof typeof data]);

Which is pretty ugly.

But it seems like you are treating data as a dictionary with string keys, rather than having specific properties of specific types. In which type data with a string index to be able to index it with arbitrary strings.

let data: { [key: string]: string } = { a: '111', b: '222' }

Upvotes: 1

Terry
Terry

Reputation: 66103

You need to add an index signature to data, i.e.:

const data: { [key: string]: string } = {
    a: '111',
    b: '222'
}

Upvotes: 1

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