Angular6 写一个简单的Select组件示例

 /src /app /select /select.ts /select.html /select.css /options.ts /index.ts 

 //select.ts import { Component, ContentChildren, ViewChild, Input, Output, EventEmitter, QueryList, HostListener } from '@angular/core'; import { NzOptionDirective } from './option'; @Component({ selector: 'nz-select', templateUrl: './select.html', styleUrls: ['./select.css'] }) export class NzSelectComponent { @Input() isOpen: boolean; @Input() value: string; @Output() valueChange = new EventEmitter(); label: string; @ContentChildren(NzOptionDirective, { descendants: true }) options: QueryList; ngAfterContentInit() { this.options.forEach(option => { option.select.subscribe(() => { this.value = option.value; this.label = option.renderLabel(); this.options.map(r => r.isSelected = false); option.isSelected = true; this.valueChange.emit(option.value); }) setTimeout(() => { option.isSelected = option.value === this.value; if (option.isSelected) { this.label = option.renderLabel(); this.valueChange.emit(option.value); } }); }) } @HostListener('click') onClick() { this.isOpen = !this.isOpen; } }

 //select.html 
{{label}}

 //select.css :host { display: inline-block; border: 1px solid; cursor: pointer; text-align: center; border-radius: 4px; } :host .current{ padding:5px 10px; background:red; color:#FFF; text-align: center; width:40px; outline: none; border: none; } ::ng-deep div:not(.current):hover{ background:green; color:#FFF; } ::ng-deep .selected { font-weight: 700; background: red; color:#FFF; } 

 //options.ts import { Directive,HostBinding,HostListener,Input,Output,ElementRef,EventEmitter} from '@angular/core'; @Directive({ selector:'[nzOption]' }) export class NzOptionDirective{ @Input() value:string; constructor(private el:ElementRef){} @Output() select = new EventEmitter(); @HostBinding("class.selected") isSelected: boolean; renderLabel(){ return (this.el.nativeElement.textContent || "").trim(); } @HostListener('click') onClick(){ this.select.emit(); } }

 //index.ts import { NzOptionDirective } from './option'; import { NzSelectComponent } from './select'; export const components = [ NzSelectComponent, NzOptionDirective ]; 

 /src /app/ /app.module.ts /app.component.ts /app.component.html 

 //app.module.ts import { NgModule } from '@angular/core'; import { BrowserModule } from '@angular/platform-browser'; import { FormsModule } from '@angular/forms'; import { CommonModule } from '@angular/common'; import {components} from './select'; import { AppComponent } from './app.component'; @NgModule({ imports:   [ BrowserModule, FormsModule,CommonModule ], declarations: [ AppComponent,...components], bootstrap:  [ AppComponent ] }) export class AppModule { } 

 //app.component.ts import { Component } from '@angular/core'; @Component({ selector: 'my-app', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { name = 'Angular'; defaultValue: any = 'value5' menus: any[] = []; ngOnInit() { for (let i = 0; i <= 6; i++) { this.menus.push({ value: 'value' + i, label: 'item' + i }) } } } 

 //app.component.html  
{{m.label}}
 select value is {{defaultValue|json}}