CODEWITHSUNDEEP
typescriptparameter-passingtslintdestructuring
Kim Gentes
Kim Gentes

Reputation: 1628

TSLint error for destructuring in function parameters

I would like to remove the tslint error I get on the following (in the object desctructuring parameter):

export function renameProperty(
    oldProp: string,
    newProp: string,
    {[oldProp]: old, ...others}
): any {
    return {
        [newProp]: old,
        ...others
    };
}

The error I get is on line 5:

TSLint: expected parameter: '{[oldProp]: old, ...others}' to have a typedef (typedef)

of course, I could do the following, but I'd rather simply do what satisfies Typescript's typing requirements.

export function renameProperty(
    oldProp: string,
    newProp: string,
    // tslint:disable-next-line:typedef
    {[oldProp]: old, ...others}
): any {
    return {
        [newProp]: old,
        ...others
    };
}

Any answers on how to type def the {[oldProp]: old, ...others} line?

Upvotes: 2

Views: 307

Answers (1)

Zbigniew Zagórski
Zbigniew Zagórski

Reputation: 1991

Interesting question, but looks like there is no definitive answer. But here is one attempt:

export function renameProperty<
    T extends {},
    OP extends keyof T,
    NP extends string,
    R = Omit<T, OP> & Record<NP, T[OP]>
>(oldProp: OP, newProp: NP, { [oldProp]: value, ...others }: T): R {
    return {
        [newProp]: value,
        ...others
    } as any; // *
}

This has advantage, that returns proper type with oldProp erased and newProp added.

i.e

const c = renameProperty("foo", "bar", { foo: 1, baz: "spam", holy: "grenade" });
console.log(c.foo, c.bar, c.baz, c.holy);
    /// complains here, that 'foo' is not available in c
    /// typeof c.bar === "number"

* Unfortunately, TS is not able to infer proper type from {[newProp]: value} and resulting type is { [x: string]: ... } so unfortunately dreadful as any is needed (at least i didn't find a way to remove it - not sure if this is a bug or limitation).

Omit: Exclude property from type

Upvotes: 1

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