patch
patch
Merges an object of type T with updates of type Partial<T>.
Returns a new object where updates override original values while not mutating the original one.
Example
interface Creature {
id: number;
type: string;
name: string;
}
const cat = { id: 1, type: 'cat' };
const catWithName = patch(cat, { name: 'Fluffy' });
// catWithName will be:
// {id: 1, type: 'cat', name: 'Fluffy'};
Example
// Usage with RxState
export class ProfileComponent {
readonly changeName$ = new Subject<string>();
constructor(private state: RxState<ComponentState>) {
// Reactive implementation
state.connect(this.changeName$, (state, name) => {
return patch(state, { name });
});
}
// Imperative implementation
changeName(name: string): void {
this.state.set(patch(this.get(), { name }));
}
}
Edge cases
patch({}, state) > state;
patch(null as any, state) > state;
patch(state, null as any) > state;
patch(null as any, null as any) > null;
patch(undefined as any, undefined as any) > undefined;
patch(state, nonObject) > state;
patch(nonObject, state) > state;
patch(nonObject, nonObjectUpdate) > nonObject;
Signature
function patch<T extends object>(object: T, upd: Partial<T>): T;