Angular changeDetction

ChangeDection

检测程序内部状态，然后反映到UI上。

引起状态变化：Events，XHR，Timers

ApplicationRef监听NgZone的onTurnDone，然后执行检测。

OnPush状态完全由外部决定，内部不会去改变状态。

例子：

把聪明组件project-list变成OnPush检查策略,

在需要检测时候使用cd.markForCheck).

@Component({
  selector: "app-project-list",
  templateUrl: "./project-list.component.html",
  styleUrls: ["./project-list.component.scss"],
  animations:[
    slideToRight,listAnimation
  ],
  changeDetection: ChangeDetectionStrategy.OnPush
})

手动告诉Angualr你来检查我

在事件发生的时候主动告诉Angular来检查这条路线。

import { Component, OnInit , HostBinding, ChangeDetectionStrategy, ChangeDetectorRef } from "@angular/core";
import { MatDialog } from "@angular/material";
import { NewProjectComponent } from "../new-project/new-project.component";
import { InviteComponent } from '../invite/invite.component';
import { ConfirmDialogComponent } from '../../shared/confirm-dialog/confirm-dialog.component';
import {slideToRight} from '../../animate/router.animate'
import { listAnimation } from '../../animate/list.animate';
import { projection } from '@angular/core/src/render3';
 
@Component({
  selector: "app-project-list",
  templateUrl: "./project-list.component.html",
  styleUrls: ["./project-list.component.scss"],
  animations:[
    slideToRight,listAnimation
  ],
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class ProjectListComponent implements OnInit {
  @HostBinding('@routeAnim') state;
 
  projects = [
    {
      id:1,
      name: "企业协作平台",
      desc: "这是一个企业内部项目",
      coverImg: "assets/images/covers/0.jpg"
    },
    {
      id:2,
      name: "自动化测试项目",
      desc: "这是一个企业内部项目",
      coverImg: "assets/images/covers/2.jpg"
    }
  ];
  constructor(private dialog: MatDialog, private cd:ChangeDetectorRef) { }
 
  ngOnInit() { }
 
  openNewProjectDialog() {
    // this.dialog.open(NewProjectComponent,{data:'this is a dialog'});
    const dialogRef = this.dialog.open(NewProjectComponent, {
      data: { title: '新建项目' }
    });
    dialogRef.afterClosed().subscribe((result) => {
      console.log(result);
      this.projects = [...this.projects,
        {id:3,name:'一个新项目',desc:'这是一个新项目',coverImg:"assets/images/covers/3.jpg"},
        {id:4,name:'又一个新项目',desc:'这是又一个新项目',coverImg:"assets/images/covers/4.jpg"}]
    });
    this.cd.markForCheck();
  }
 
  lauchInviteDialog() {
    const dialogRef = this.dialog.open(InviteComponent);
  }
 
  lauchUpdateDialog() {
    const dialogRef = this.dialog.open(NewProjectComponent, {
      data: { title: '编辑项目' }
    });
  }
 
  lauchConfimDialog(project) {
    const dialogRef = this.dialog.open(ConfirmDialogComponent, {
      data: { title: '删除项目', content: '您确认删除该项目吗？' }
    });
    dialogRef.afterClosed().subscribe(result=>{
      console.log(result);
      this.projects=this.projects.filter(p=>p.id!=project.id);
      this.cd.markForCheck();
    });
  }
}

把笨组件标识为OnPush

直接加changeDetection:ChangeDetectionStrategy.OnPush

@Component({
  selector: 'app-new-project',
  templateUrl: './new-project.component.html',
  styleUrls: ['./new-project.component.scss'],
  changeDetection:ChangeDetectionStrategy.OnPush
})