Typescript destructuring with required parameter
You use a default value {}
for the PageConfig constructor argument, but you marked getList
as required in the type. If I understand you correctly, you want to have the constructor argument and getList
always set, so change your code to:
export class PageConfig {
constructor({
getList,
isSliding = false
}: {
getList: (pagingInfo: PagingInfo) => Observable<any>;
isSliding?: boolean;
}) {
… // use getList and isSliding
}
}
This syntax (destructuring with default values) can be a bit cumbersome sometimes. It gets clearer, when you extract the constructor argument type.
TypeScript docs example
You want to remove the default, and also change the parameter order - required parameters always come before optional parameters:
constructor(getList: (pagingInfo: PagingInfo) => Observable<any>, isSliding?: boolean = false) {...}
One option if it is the case that all constructor parameters are optional/have a default value would be simply to use a Partial config in the constructor and merge with defaults, e.g.
interface IPageConfigConstructor {
isSliding: boolean;
getList: (pagingInfo) => Observable<any>;
}
const DEFAULT_CONFIG:IPageConfigConstructor = {
isSliding: true,
getList: (pagingInfo) => null
}
class PageConfig {
constructor(config: Partial<IPageConfigConstructor>) {
const mergedConfig:IPageConfigConstructor = {...DEFAULT_CONFIG,...config}
}
}
class UsersPage {
config = new PageConfig({getList:(pagingInfo)=>this.getList(pagingInfo)});
getList(pagingInfo) {
// do work...
return new Observable
}
}