app.service.ts
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import { Injectable } from '@angular/core';
export type InternalStateType = {
[key: string]: any
};
@Injectable()
export class AppState {
_state: InternalStateType = {};
constructor() {
}
// already return a clone of the current state
get state() {
return this._state = this._clone(this._state);
}
// never allow mutation
set state(value) {
throw new Error('do not mutate the `.state` directly');
}
get(prop?: any) {
// use our state getter for the clone
const state = this.state;
return state.hasOwnProperty(prop) ? state[prop] : state;
}
set(prop: string, value: any) {
// internally mutate our state
return this._state[prop] = value;
}
private _clone(object: InternalStateType) {
// simple object clone
return JSON.parse(JSON.stringify(object));
}
}