要使localStorage在Angular中异步工作,你可以使用RxJS的Observables和Subject来实现。以下是一个示例代码:
首先,创建一个LocalStorageService服务,用于处理localStorage的读取和写入操作。
import { Injectable } from '@angular/core';
import { Observable, Subject } from 'rxjs';
@Injectable({
providedIn: 'root'
})
export class LocalStorageService {
private storageSubject = new Subject();
constructor() {
window.addEventListener('storage', (event) => {
if (event.storageArea === localStorage) {
this.storageSubject.next(event.key);
}
});
}
getItem(key: string): Observable {
return new Observable((observer) => {
observer.next(localStorage.getItem(key));
observer.complete();
});
}
setItem(key: string, value: string): Observable {
return new Observable((observer) => {
localStorage.setItem(key, value);
observer.next(true);
observer.complete();
});
}
watchStorageChanges(): Observable {
return this.storageSubject.asObservable();
}
}
在上面的代码中,我们使用了Subject来创建一个可观察对象storageSubject,以便在localStorage发生更改时通知订阅者。我们通过监听window的storage事件来实现这一点。
LocalStorageService提供了三个方法:
接下来,你可以在组件中使用LocalStorageService来进行异步操作。
import { Component, OnInit } from '@angular/core';
import { LocalStorageService } from './local-storage.service';
@Component({
selector: 'app-example',
template: `
`
})
export class ExampleComponent implements OnInit {
constructor(private localStorageService: LocalStorageService) {}
ngOnInit() {}
getItem() {
this.localStorageService.getItem('key').subscribe((value) => {
console.log(value);
});
}
setItem() {
this.localStorageService.setItem('key', 'value').subscribe((success) => {
console.log(success);
});
}
}
在上面的示例代码中,我们注入了LocalStorageService,并在两个按钮的点击事件中调用了getItem和setItem方法来进行异步读取和写入localStorage的操作。
最后,你可以使用watchStorageChanges方法来监听localStorage的变化。
import { Component, OnInit } from '@angular/core';
import { LocalStorageService } from './local-storage.service';
@Component({
selector: 'app-example',
template: `
{{ value }}
`
})
export class ExampleComponent implements OnInit {
value: string;
constructor(private localStorageService: LocalStorageService) {}
ngOnInit() {
this.localStorageService.watchStorageChanges().subscribe((key) => {
if (key === 'key') {
this.localStorageService.getItem('key').subscribe((value) => {
this.value = value;
});
}
});
}
}
在上面的示例代码中,我们通过订阅watchStorageChanges方法返回的可观察对象来监听localStorage的变化。当键为'key'的localStorage发生变化时,我们重新获取其值并更新组件的value属性。
通过上述代码示例,你可以在Angular中实现异步操作localStorage的功能。