I want to create a new operator like map. but the different is whatever map returns I need to clone it using JSON.parse(JSON.stringify(value)).

Because I return an object from my store (Subject), and I don't want somebody to change it, or it's inner properties.

I copy the map singture to my mapToVM function, but I can't find any way to use pipe or manipulate the return results.

Is it possible to change the return results by wrapping the map operator?

codesandbox

So I try to return the map function and take the source as Observable, but typescript

import { map, Observable, OperatorFunction, Subject } from "rxjs";

console.clear();

const store = new Subject<{ company: { id: number } }>();

store.pipe(map((s) => s.company)).subscribe((company) => {
  console.log({ company });
});

function mapToVM<T, R>(
  project: (value: T, index: number) => R
): OperatorFunction<T, R> {
  // JSON.parse(JSON.stringify(source));
  return map(project);
}

store.pipe(mapToVM((s) => s.company)).subscribe((company) => {
  console.log({ company });
});

store.next({ company: { id: 1 } });

CodePudding user response：

you can use the static pipe function:

function jsonClone<T>(): OperatorFunction<T, T> {
  return pipe(map((source) => JSON.parse(JSON.stringify(source))));
}

Full CodeSandbox example