Assigning values to object properties in a TypeScript loop

Question

Assigning values to object properties in a TypeScript loop

I need to update a Feature object in my code. Here is a simplified version of the structure:

type Feature = {id: number, name: string, deletedAt?: Date}

const newData: Partial<Feature> & {id: number} = {
    id: 1, deletedAt: new Date()
};
const oldFeature: Feature = {
    id: 1, name: 'Abc', deletedAt: undefined
};

for (const key of Object.keys(newData) as (keyof Feature)[]) {
    oldFeature[key] = newData[key];
}

Both oldFeature[key] and newData[key] have types of

string | number | Date | undefined

. However, despite having the same possible types for each given key in both objects, I am encountering an error when trying to make the assignment oldFeature[key] = newData[key]:

Type 'string | number | Date | undefined' is not assignable to type 'never'.
Type 'undefined' is not assignable to type 'never'.ts(2322)

Why is this happening? And what is the proper way to handle this issue?

typescript typing

Answer 1

Answer №1

Instead of using a loop, I found a more efficient solution by utilizing object spreading in my code:

const updated = {
    ...oldFeature,
    ...newData,
}

This approach effectively updates the necessary fields without unnecessary overhead.

Answer 2

Instead of using a loop, I found a more efficient solution by utilizing object spreading in my code:

const updated = {
    ...oldFeature,
    ...newData,
}

This approach effectively updates the necessary fields without unnecessary overhead.

Assigning values to object properties in a TypeScript loop

Answer №1

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