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[Angular 2] @Input & @Output Event with ref

ampAngular with input Event ref output
2023-09-14 08:59:19 时间

The application is simple, to build a color picker:

When click the rect box, it will check the color value below and title color will also change.

 

color-picker.ts:

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

import {RED, BLUE} from './constants';

@Component({
    selector: 'color-picker',
    moduleId: module.id,
    templateUrl: 'color-picker.component.html'
})
export class ColorPicker{
    @Input() color:string;
    @Output('selectedColor') colorOut = new EventEmitter();

    red = RED;
    blue = BLUE;

    choose(color){
        this.colorOut.emit(color);
    }
}

color-picker.component.html:

<div class="color-title" [ngStyle]="{color:color}">Pick a Color, plz:</div>

<div class="color-picker">
    <div class="color-sample color-sample-blue" (click)="choose(red)"></div>
    <div class="color-sample color-sample-red" (click)="choose(blue)"></div>
</div>

 

So the logic is we will take a color input, it is used in title styling:

<div class="color-title" [ngStyle]="{color:color}">Pick a Color, plz:</div>

When we click on one rect box, fire choose() function, it will output a event named "selectedColor":

@Output('selectedColor') colorOut = new EventEmitter();

    choose(color){
        this.colorOut.emit(color);
    }

If we don't give name 'selectorColor', it will used 'colorOut' as name.

In app.ts, it is used:

            <color-picker #picker [color]="picker.color" (selectedColor)="picker.color = $event">  
            </color-picker>
            {{picker.color}}

Here we use reference:

#picker

And we assign the color back from output event to picker.color, this picker.color then will be used as input to color-pick to change the title color.

 

The benfits to use reference is avoid assign a local variable.

 

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