angular2 ng2 @input and @output understanding and examples

angular2 @input and @output understand

Make an example first, and then provide the code

for example:

<talk-cmp [talk]="someExp" (rate)="eventHandler($)">

input, [talk]="someExp" tag can be understood as a special listener that monitors someExp parameters passed by the parent component and stores the talk change of its own component; it seems that a backdoor is opened, allowing only someExp of the parent component to enter. Once entered, it is immediately grabbed into a cell called talk, and then the child component can define this variable talk through @Input and use it.

output , (click)="eventHandler($) This means that when the click event of the child component is triggered, the eventHandler function of the parent component is executed, and the parameter $ of the child component is passed to the eventHandler function of the parent component; it is like when the child cries (executes the click event), his mother immediately holds him in his arms (executes the mother's eventHandler), and the mother obtains some parameters of the child ($)

1、@input()

Parent component provides data

import {Component} from "@angular/core";
@Component({
  selector: "my-father",
  templateUrl: ""
})
export class FatherComponent {
  data: Array<Object>;
  constructor() {
     = [
      {
        "id": 1,
        "name": "html"
      },
      {
        "id": 2,
        "name": "css"
      },
      {
        "id": 3,
        "name": "angular"
      },
      {
        "id": 4,
        "name": "ionic"
      },
      {
        "id": 5,
        "name": "node"
      }
    ]
  }
}

Template file

&lt;h1&gt;Parent component&lt;/h1&gt;
// Contains child components and uses properties to pass data past&lt;my-child [info]="data"&gt;&lt;/my-child&gt;

Subcomponents Get data

import {Component, Input} from "@angular/core";
@Component({
  selector: "my-child",
  templateUrl: ""
})
export class ChildComponent {  
  // Use @Input to get the passed data  @Input()
  info: Array&lt;Object&gt;;
  constructor() {
  
  }
}

Subcomponents Template File

<ul>
  <li *ngFor="let item of info">
    {{}}
  </li>
</ul>

2、@Output()

Subcomponents

1. Introduce

import {Component, OnInit, Output, EventEmitter} from "@angular/core";

2. Define output variables

export class ThreeLinkComponent {
  province: string;
  // Output the parameters  @Output() provinceOut = new EventEmitter();  
  constructor() {
     = "Shaanxi";
  } 
}

3. Starting from the event, transmitting variables to the parent component

provinceChange() {
  // When selecting a province, launch the province to the parent component  ();
}

Parent component template

&lt;!--Three-level linkage components--&gt;
&lt;three-link (provinceOut)="recPro($event)"&gt;&lt;/three-link&gt;

Parent component

// The function accepts variables passed by the subfunction, and this function is triggered when emitted in the subfunction.recPro(event) {
   = event;
}

The above is all the content of this article. I hope it will be helpful to everyone's study and I hope everyone will support me more.