响应式
声明状态
更新状态
Angular Renaissance
import { Component, signal } from "@angular/core";
@Component({
selector: "app-name",
template: `<h1>你好 {{ name() }}</h1>`,
})
export class NameComponent {
name = signal("张三");
constructor() {
this.name.set("李四");
}
}
计算属性
Angular Renaissance
import { Component, computed, signal } from "@angular/core";
@Component({
selector: "app-double-count",
template: `<div>{{ doubleCount() }}</div>`,
})
export class DoubleCountComponent {
count = signal(10);
doubleCount = computed(() => this.count() * 2);
}
模板语法
最简模板
样式
Angular Renaissance
import { Component } from "@angular/core";
@Component({
selector: "app-css-style",
template: `
<h1 class="title">我是红色的</h1>
<button style="font-size: 10rem">我是一个按钮</button>
`,
styles: `
.title {
color: red;
}
`,
})
export class CssStyleComponent {}
DOM循环
Angular Renaissance
import { Component } from "@angular/core";
@Component({
selector: "app-colors",
template: `
<ul>
@for (color of colors; track color) {
<li>{{ color }}</li>
}
</ul>
`,
})
export class ColorsComponent {
colors = ["红", "绿", "蓝"];
}
点击事件
Angular Renaissance
import { Component, signal } from "@angular/core";
@Component({
selector: "app-counter",
template: `
<p>计数器: {{ count() }}</p>
<button (click)="incrementCount()">+1</button>
`,
})
export class CounterComponent {
count = signal(0);
incrementCount() {
this.count.update((count) => count + 1);
}
}
DOM引用
Angular Renaissance
import {
afterNextRender,
Component,
ElementRef,
viewChild,
} from "@angular/core";
@Component({
selector: "app-input-focused",
template: `<input type="text" #inputRef />`,
})
export class InputFocusedComponent {
inputRef = viewChild.required<ElementRef<HTMLInputElement>>("inputRef");
constructor() {
afterNextRender({ write: () => this.inputRef().nativeElement.focus() });
}
}
条件渲染
Angular Renaissance
import { Component, computed, signal } from "@angular/core";
const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];
@Component({
selector: "app-traffic-light",
template: `
<button (click)="nextLight()">下一个灯</button>
<p>现在亮着的是: {{ light() }}</p>
<p>
你应该
@switch (light()) {
@case ("红灯") {
<span>停下</span>
}
@case ("黄灯") {
<span>慢行</span>
}
@case ("绿灯") {
<span>赶紧走</span>
}
}
</p>
`,
})
export class TrafficLightComponent {
lightIndex = signal(0);
light = computed(() => TRAFFIC_LIGHTS[this.lightIndex()]);
nextLight() {
this.lightIndex.update((index) => (index + 1) % TRAFFIC_LIGHTS.length);
}
}
static const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];
<let/lightIndex=0>
<const/light=TRAFFIC_LIGHTS[lightIndex]>
<button onClick() { lightIndex = (lightIndex + 1) % TRAFFIC_LIGHTS.length }>
下一个灯
</button>
<p>现在亮着的是: ${light}</p>
<p>
你应该
<if=light === "红灯">停下</if>
<else if=light === "黄灯">慢行</else>
<else>赶紧走</else>
</p>
生命周期
组件加载时
Angular Renaissance
import { Component, OnInit, signal } from "@angular/core";
@Component({
selector: "app-page-title",
template: `<p>页面标题: {{ pageTitle() }}</p>`,
})
export class PageTitleComponent implements OnInit {
pageTitle = signal("");
ngOnInit() {
this.pageTitle.set(document.title);
}
}
组件卸载时
Angular Renaissance
import { Component, OnDestroy, signal } from "@angular/core";
@Component({
selector: "app-time",
template: `<p>当前时间: {{ time() }}</p>`,
})
export class TimeComponent implements OnDestroy {
time = signal(new Date().toLocaleTimeString());
timer = setInterval(
() => this.time.set(new Date().toLocaleTimeString()),
1000,
);
ngOnDestroy() {
clearInterval(this.timer);
}
}
组件组合
组件Props传参
Angular Renaissance
import { Component } from "@angular/core";
import { UserprofileComponent } from "./userprofile.component";
@Component({
selector: "app-root",
imports: [UserprofileComponent],
template: `
<app-userprofile
name="张三"
[age]="20"
[favouriteColors]="['green', 'blue', 'red']"
[isAvailable]="true"
/>
`,
})
export class AppComponent {}
向父组件emit事件
Angular Renaissance
import { Component, signal } from "@angular/core";
import { AnswerButtonComponent } from "./answer-button.component";
@Component({
selector: "app-root",
imports: [AnswerButtonComponent],
template: `
<p>你快乐吗?</p>
<app-answer-button (yes)="onAnswerYes()" (no)="onAnswerNo()" />
<p style="font-size: 50px">{{ isHappy() ? "😀" : "😥" }}</p>
`,
})
export class AppComponent {
isHappy = signal(true);
onAnswerYes() {
this.isHappy.set(true);
}
onAnswerNo() {
this.isHappy.set(false);
}
}
slot插槽
Angular Renaissance
import { Component } from "@angular/core";
import { FunnyButtonComponent } from "./funny-button.component";
@Component({
selector: "app-root",
imports: [FunnyButtonComponent],
template: `<app-funny-button>点我!</app-funny-button>`,
})
export class AppComponent {}
slot插槽内容
Angular Renaissance
import { Component } from "@angular/core";
import { FunnyButtonComponent } from "./funny-button.component";
@Component({
selector: "app-root",
imports: [FunnyButtonComponent],
template: `
<app-funny-button />
<app-funny-button>这是传到slot的内容!</app-funny-button>
`,
})
export class AppComponent {}
上下文
Angular Renaissance
import { Component, inject } from "@angular/core";
import { UserService } from "./user.service";
import { UserProfileComponent } from "./user-profile.component";
@Component({
imports: [UserProfileComponent],
providers: [UserService],
selector: "app-root",
template: `
<h1>欢迎回来, {{ userService.user().username }}</h1>
<app-user-profile />
`,
})
export class AppComponent {
protected userService = inject(UserService);
}
<let/user={
id: 1,
username: "abcdefg",
email: "[email protected]",
}>
<const/updateUsername(newUsername) {
user = { ...user, username: newUsername };
}>
<h1>欢迎回来, ${user.username}</h1>
<context={ ...user, updateUsername }>
<UserProfile />
</context>
表单输入
输入框
Angular Renaissance
import { Component, signal } from "@angular/core";
import { FormsModule } from "@angular/forms";
@Component({
imports: [FormsModule],
selector: "app-input-hello",
template: `
<p>{{ text() }}</p>
<input [(ngModel)]="text" />
`,
})
export class InputHelloComponent {
text = signal("");
}
复选框
Angular Renaissance
import { Component, signal } from "@angular/core";
import { FormsModule } from "@angular/forms";
@Component({
imports: [FormsModule],
selector: "app-is-available",
template: `
<input id="is-available" type="checkbox" [(ngModel)]="isAvailable" />
<label for="is-available">这是一个checkbox</label>
`,
})
export class IsAvailableComponent {
isAvailable = signal(false);
}
单选框
Angular Renaissance
import { Component, signal } from "@angular/core";
import { FormsModule } from "@angular/forms";
@Component({
imports: [FormsModule],
selector: "app-pick-pill",
template: `
<div>你选择了: {{ picked() }}</div>
<input id="blue-pill" type="radio" value="blue" [(ngModel)]="picked" />
<label for="blue-pill">蓝色</label>
<input id="red-pill" type="radio" value="red" [(ngModel)]="picked" />
<label for="red-pill">红色</label>
`,
})
export class PickPillComponent {
picked = signal("red");
}
选择器
Angular Renaissance
import { Component, signal } from "@angular/core";
import { FormsModule } from "@angular/forms";
@Component({
imports: [FormsModule],
selector: "app-color-select",
template: `
<select [(ngModel)]="selectedColorId">
@for (let color of colors; track color) {
<option [value]="color.id" [disabled]="color.isDisabled">
{{ color.text }}
</option>
}
</select>
`,
})
export class ColorSelectComponent {
selectedColorId = signal(2);
colors = [
{ id: 1, text: "红" },
{ id: 2, text: "蓝" },
{ id: 3, text: "绿" },
{ id: 4, text: "灰", isDisabled: true },
];
}
static const colors = [
{ id: 1, text: "红" },
{ id: 2, text: "蓝" },
{ id: 3, text: "绿" },
{ id: 4, text: "灰", isDisabled: true },
];
<let/selectedColorId=2>
<select value:=selectedColorId>
<for|{ id, isDisabled, text }| of=colors>
<option value=id disabled=isDisabled>
${text}
</option>
</for>
</select>
Web应用特性
渲染应用
fetch获取数据
Angular Renaissance
import { Injectable } from "@angular/core";
import { httpResource } from "@angular/common/http";
@Injectable({ providedIn: "root" })
export class UserService {
readonly usersResource = httpResource<UserResponse>(
() => "https://randomuser.me/api/?results=3",
);
}
export interface UserResponse {
results: User[];
info: any;
}
export interface User {
name: {
title: string;
first: string;
last: string;
};
picture: {
large: string;
medium: string;
thumbnail: string;
};
}
<try>
<await|{ results: users }|=fetch("https://randomuser.me/api/?results=3").then(res => res.json())>
<ul>
<for|{ picture, name }| of=users>
<li>
<img src=picture.thumbnail alt="user">
<p>${name.first} ${name.last}</p>
</li>
</for>
</ul>
</await>
<@placeholder>
<p>正在获取用户信息……</p>
</@placeholder>
<@catch|error|>
<p>获取用户信息出错</p>
</@catch>
</try>