typescript 如何在 angular 2 中从 localstorage 订阅项目，并在更改时获取值
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how to subscribe an item from localstorage in angular 2 and when changed, get value
提问by Ankit Singh
I'm trying to create an application with angular 2, and my problem is how to subscribe an item from local storage... I know I must use a service, only access LocalStorage through this service from everywhere, but I don't know how this can be done.
我正在尝试使用 angular 2 创建一个应用程序，我的问题是如何从本地存储订阅项目...我知道我必须使用一项服务，只能从任何地方通过此服务访问 LocalStorage，但我不知道如何做到这一点。
回答by Ankit Singh
For a basic Idea this is how it can be done.
对于一个基本的想法，这是如何做到的。
Just need to write the correct Import paths accotding to your configuration
只需要根据您的配置编写正确的导入路径
Write a global service:
编写一个全局服务：
import {BehaviorSubject} from 'rxjs';
@Injectable({provideIn: 'root'})
export class GlobalService {
itemValue = new BehaviorSubject(this.theItem);
set theItem(value) {
this.itemValue.next(value); // this will make sure to tell every subscriber about the change.
localStorage.setItem('theItem', value);
}
get theItem() {
return localStorage.getItem('theItem');
}
}
Usage:
用法：
- Any change here
- 这里有任何变化
@Component({})
export class SomeComponent {
constructor(private globalSrv: GlobalService){}
someEvent() {
this.globalSrv.theItem = 'someValue'; // this change will broadcast to every subscriber like below component
}
}
- Will Reflect Here
- 会反映在这里
@Component({})
export class AnotherComponent {
constructor(private globalSrv: GlobalService){
globalSrv.itemValue.subscribe((nextValue) => {
alert(nextValue); // this will happen on every change
})
}
}
