onInit上的可观察订阅仅运行一次

import { Component, OnInit, OnDestroy } from '@angular/core';
import { Subject } from 'rxjs';
import { takeUntil } from 'rxjs/operators';

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class ExampleComponent implements OnInit, OnDestroy {
  private destroy$ = new Subject<void>();

  ngOnInit() {
    someObservable$.pipe(
      takeUntil(this.destroy$)
    ).subscribe(data => {
      // 处理数据
    });
  }

  ngOnDestroy() {
    this.destroy$.next();
    this.destroy$.complete();
  }
}

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class ExampleComponent implements OnInit {
  ngOnInit() {
    someObservable$.pipe(
      take(1)
    ).subscribe(data => {
      // 处理数据
    });
  }
}

import { Component, OnInit, OnDestroy } from '@angular/core';
import { Subscription } from 'rxjs';

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class ExampleComponent implements OnInit, OnDestroy {
  private subscription: Subscription;

  ngOnInit() {
    this.subscription = someObservable$.subscribe(data => {
      // 处理数据
    });
  }

  ngOnDestroy() {
    if (this.subscription) {
      this.subscription.unsubscribe();
    }
  }
}