Expand type by incorporating a rest parameter

Question

Expand type by incorporating a rest parameter

There's a specific type that I have in mind

export type baseEventType = {
    eName: string;
    mName: string;
    
};

and my goal is to enhance it by incorporating a rest parameter

interface gEvent extends baseEventType {
    ...rest: any[]
}

although this approach seems impractical

I envisioned utilizing it in this fashion

export const save = ({ eName, mName, ...rest }: gEvent) =>

Is there a way to make this concept functional? While the following alternative is feasible

export const save = (eName: string, mName: string, ...rest: any[]) => {

I would prefer to implement something akin to the initial structure.

typescript

Answer 1

Answer №1

To allow for additional properties in the gEvent type without compromising type checking, consider adding an index signature:

export type baseEventType = {
    eName: string;
    mName: string;
};
interface gEvent extends baseEventType {
    [name: string]: any;
}

export const save = ({ eName, mName, ...rest }: gEvent) => {

}

save({
  eName: 0 // While eName is declared as a string, passing a number is possible due to the index signature
})

Playground Link

Alternatively, using an intersection type would be more appropriate for robust type checking of named properties:

type gEvent = baseEventType & {
    [name: string]: any;
}

export const save = ({ eName, mName, ...rest }: gEvent) => {

}

save({
  eName: 0, // this will result in an error
  other: "", // this is acceptable
})

Playground Link

Answer 2

To allow for additional properties in the gEvent type without compromising type checking, consider adding an index signature:

export type baseEventType = {
    eName: string;
    mName: string;
};
interface gEvent extends baseEventType {
    [name: string]: any;
}

export const save = ({ eName, mName, ...rest }: gEvent) => {

}

save({
  eName: 0 // While eName is declared as a string, passing a number is possible due to the index signature
})

Playground Link

Alternatively, using an intersection type would be more appropriate for robust type checking of named properties:

type gEvent = baseEventType & {
    [name: string]: any;
}

export const save = ({ eName, mName, ...rest }: gEvent) => {

}

save({
  eName: 0, // this will result in an error
  other: "", // this is acceptable
})

Playground Link

Expand type by incorporating a rest parameter

Answer №1

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