Detailed explanation of how to manipulate DOM elements in angular

How to correctly manipulate DOM elements in Angular? The following article will introduce to you how to operate DOM elements in angular. I hope it will be helpful to you!

To obtain DOM elements in angular, you can use javascript's native API, or introduce jQuery through jquery objectOperation DOM, but angular has provided us with the corresponding API (ElementRef) to obtain DOM elements, so there is no need to use the native API or jQuery. [Related tutorial recommendations: "angular tutorial"]

ElementRef Get the DOM element

1. Create TestComponentComponent, the template is as follows: test.component.html

<div>
	<p>你好</p>
</div>
<div>
    <span>世界</span>
</div>
<h1>标题</h1>
<pass-badge id="component" textColor="red">组件</pass-badge>

2. Write the test.component.ts file

import { Component, OnInit } from '@angular/core';
// 1、导入 ElementRef 类
import { ElementRef} from '@angular/core';
import { PassBadge } from './compoment/pass-badge/pass-badge.component'

@Component({
  selector: 'app-test',
  templateUrl: './test.component.html',
  styleUrls: ['./test.component.css'],
  declarations: [ PassBadge ]
})
export class TestComponent implements OnInit {
	// 2、将 ElementRef 类注入 test 组件中
    constructor(private el:ElementRef) {}

    ngOnInit() {
    	// 3、获取 DOM 元素
        console.log(this.el.nativeElement)
        console.log(this.el.nativeElement.querySelector('#component'))
    }
}

us Let’s see what this.el.nativeElement is

So you can pass this.el.nativeElement.querySelector('#component' ) to operate the corresponding DOM element. For example, you can change the text color

this.el.nativeElement.querySelector('#component').style.color = 'lightblue'

Template variable to get the DOM element

You can get the component throughViewChild, and the same isContentChild, ViewChildren and ContentChildren

1. Modify the TestComponent component and add template variables to the corresponding elements. , as follows

<div>
    <p>你好</p>
</div>
<!-- 1、给元素加入模板变量 div -->
<div #div>
    <span>世界</span>
</div>
<h1>标题</h1>
<!-- 给组件加入模板变量 component -->
<pass-badge #component textColor="red">组件</pass-badge>

2. Modify test.component.ts as follows:

import { Component, OnInit } from '@angular/core';
import { ElementRef} from '@angular/core';
// 2、引入ViewChild
import { ViewChild } from '@angular/core'

@Component({
  selector: 'app-test',
  templateUrl: './test.component.html',
  styleUrls: ['./test.component.css']
})
export class TestComponent implements OnInit {
    constructor(private el:ElementRef) {}
    // 3、获取元素
    @ViewChild('component') dom: any;
    @ViewChild('div') div: any;
    ngOnInit() {
        console.log(this.dom)	// PassBadgeComponent
        this.dom.fn()   // 调用 passbadge 组件的 fn 方法
        console.log(this.div)	// ElementRef
        this.div.nativeElement.style.color = 'lightblue'	// 文字颜色修改为淡蓝色
    }
}

The final result is as follows

We can know from the results that when using the ViewChild template variable to obtain the component element, what is obtained is the component class exported by the component (the above example is PassBadgeComponent). At this time Only properties contained in the component can be manipulated.

When using the ViewChild template variable to obtain the html element, the class obtained is the ElementRef type. At this time, you can pass this.div.nativeElement. querySelector('span') and other native APIs to operate elements

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