logo

Component Party

Reactivity

Declare state

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import { Component, NgModule } from "@angular/core";

@Component({
  selector: "app-name",
  template: `<h1>Hello {{ name }}</h1>`,
})
export class NameComponent {
  name = "John";
}

@NgModule({
  declarations: [NameComponent],
  exports: [NameComponent],
})
export class NameModule {}

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import m from "mithril";

export default function Name() {
  let name = "John";

  return {
    view: () => m("h1", `Hello ${name}`),
  };
}

Update state

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import { Component, NgModule } from "@angular/core";

@Component({
  selector: "app-name",
  template: `<h1>Hello {{ name }}</h1>`,
})
export class NameComponent {
  name = "John";

  constructor() {
    this.name = "Jane";
  }
}

@NgModule({
  declarations: [NameComponent],
  exports: [NameComponent],
})
export class NameModule {}

logo of Mithril Mithril

import m from "mithril";

export default function Name() {
  let name = "John";
  name = "Jane";
  return {
    view: () => m("h1", `Hello ${name}`),
  };
}

Computed state

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import { Component, NgModule } from "@angular/core";

@Component({
  selector: "app-doublecount",
  template: `<div>{{ doubleCount }}</div>`,
})
export class DoublecountComponent {
  count = 10;

  get doubleCount() {
    return this.count * 2;
  }
}

@NgModule({
  declarations: [DoublecountComponent],
  exports: [DoublecountComponent],
})
export class DoublecountModule {}

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import m from "mithril";

export default function DoubleCount() {
  let count = 10;
  let doubleCount = count * 2;
  return {
    view: () => m("div", doubleCount),
  };
}

Templating

Minimal template

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import { Component, NgModule } from "@angular/core";

@Component({
  selector: "app-helloworld",
  template: `<h1>Hello world</h1>`,
})
export class HelloworldComponent {}

@NgModule({
  declarations: [HelloworldComponent],
  exports: [HelloworldComponent],
})
export class HelloworldModule {}

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import m from "mithril";

export default function HelloWorld() {
  return {
    view: () => m("h1", "Hello World"),
  };
}

Styling

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import { Component, NgModule } from "@angular/core";

@Component({
  selector: "app-cssstyle",
  template: `
    <h1 class="title">I am red</h1>
    <button style="font-size: 10rem">I am a button</button>
  `,
  styles: [
    `
      .title {
        color: red;
      }
    `,
  ],
})
export class CssStyleComponent {}

@NgModule({
  declarations: [CssStyleComponent],
  exports: [CssStyleComponent],
})
export class CssStyleModule {}

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import "./style.css";
import m from "mithril";

export default function CssStyle() {
  return {
    view: () =>
      m(
        "div",
        m("h1.title", "I am red"),
        m("button", { style: { fontSize: "10rem" } }, "I am a button"),
      ),
  };
}

Loop

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import { Component, NgModule } from "@angular/core";
import { CommonModule } from "@angular/common";

@Component({
  selector: "app-colors",
  template: `
    <ul>
      <li *ngFor="let color of colors">{{ color }}</li>
    </ul>
  `,
})
export class ColorsComponent {
  colors = ["red", "green", "blue"];
}

@NgModule({
  declarations: [ColorsComponent],
  imports: [CommonModule],
  exports: [ColorsComponent],
})
export class ColorsModule {}

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import m from "mithril";

export default function Colors() {
  const colors = ["red", "green", "blue"];
  return {
    view: () =>
      m(
        "ul",
        colors.map((color, idx) => m("li", { key: idx }, color)),
      ),
  };
}

Event click

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import { Component, NgModule } from "@angular/core";

@Component({
  selector: "app-counter",
  template: `
    <p>Counter: {{ count }}</p>
    <button (click)="incrementCount()">+1</button>
  `,
})
export class CounterComponent {
  count = 0;

  incrementCount() {
    this.count++;
  }
}

@NgModule({
  declarations: [CounterComponent],
  exports: [CounterComponent],
})
export class CounterModule {}

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import m from "mithril";

export default function Counter() {
  let count = 0;
  const incrementCount = () => (count = count + 1);
  return {
    view: () =>
      m(
        "div",
        m("p", `Counter: ${count}`),
        m("button", { onclick: incrementCount }, "+1"),
      ),
  };
}

Dom ref

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import {
  Component,
  ViewChild,
  ElementRef,
  OnInit,
  NgModule,
} from "@angular/core";

@Component({
  selector: "app-inputfocused",
  template: `<input type="text" #inputRef />`,
})
export class InputfocusedComponent implements OnInit {
  @ViewChild("inputRef", { static: true })
  inputRef!: ElementRef<HTMLInputElement>;

  ngOnInit() {
    this.inputRef.nativeElement.focus();
  }
}

@NgModule({
  declarations: [InputfocusedComponent],
  exports: [InputfocusedComponent],
})
export class InputfocusedModule {}

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import m from "mithril";

export default function InputFocused() {
  let value = "";
  return {
    view: () =>
      m("input", {
        oncreate: ({ dom }) => dom.focus(),
        type: "text",
        value,
        oninput: (e) => (value = e.target.value),
      }),
  };
}

Conditional

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import { Component, NgModule } from "@angular/core";
import { CommonModule } from "@angular/common";

const TRAFFIC_LIGHTS = ["red", "orange", "green"];

@Component({
  selector: "app-trafficlight",
  template: `
    <button (click)="nextLight()">Next light</button>
    <p>Light is: {{ light }}</p>
    <p>
      You must
      <ng-container [ngSwitch]="light">
        <span *ngSwitchCase="'red'">STOP</span>
        <span *ngSwitchCase="'orange'">SLOW DOWN</span>
        <span *ngSwitchCase="'green'">GO</span>
      </ng-container>
    </p>
  `,
})
export class TrafficlightComponent {
  lightIndex = 0;

  get light() {
    return TRAFFIC_LIGHTS[this.lightIndex];
  }

  nextLight() {
    this.lightIndex = (this.lightIndex + 1) % TRAFFIC_LIGHTS.length;
  }
}

@NgModule({
  declarations: [TrafficlightComponent],
  imports: [CommonModule],
  exports: [TrafficlightComponent],
})
export class TrafficlightModule {}

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import m from "mithril";
const TRAFFIC_LIGHTS = ["red", "orange", "green"];

export default function TrafficLight() {
  let lightIndex = 0;
  let currentLight = () => TRAFFIC_LIGHTS[lightIndex];

  const nextLight = () => (lightIndex + 1) % TRAFFIC_LIGHTS.length;

  const instructions = () => {
    switch (currentLight()) {
      case "red":
        return "STOP";
      case "orange":
        return "SLOW DOWN";
      case "green":
        return "GO";
    }
  };

  return {
    view: () =>
      m(
        "div",
        m("button", { onclick: nextLight }, "Next light"),
        m("p", `Light is: ${currentLight()}`),
        m("p", "You must ", m("span", instructions())),
      ),
  };
}

Lifecycle

On mount

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

@Component({
  selector: "app-pagetitle",
  template: `<p>Page title: {{ pageTitle }}</p>`,
})
export class PagetitleComponent implements OnInit {
  pageTitle = "";

  ngOnInit() {
    this.pageTitle = document.title;
  }
}

@NgModule({
  declarations: [PagetitleComponent],
  exports: [PagetitleComponent],
})
export class PagetitleModule {}

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import m from "mithril";

export default function PageTitle() {
  return {
    view: () => m("p", `Page title: ${document.title}`),
  };
}

On unmount

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import { Component, NgModule, OnDestroy } from "@angular/core";

@Component({
  selector: "app-time",
  template: `<p>Current time: {{ time }}</p>`,
})
export class TimeComponent implements OnDestroy {
  time = new Date().toLocaleTimeString();

  timer = setInterval(() => {
    this.time = new Date().toLocaleTimeString();
  }, 1000);

  ngOnDestroy() {
    clearInterval(this.timer);
  }
}

@NgModule({
  declarations: [TimeComponent],
  exports: [TimeComponent],
})
export class TimeModule {}

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import m from "mithril";

export default function Time() {
  let time = new Date().toLocaleTimeString();

  const timer = setInterval(() => {
    time = new Date().toLocaleTimeString();
    m.redraw();
  }, 1000);

  return {
    view: () => m("p", `Current time: ${time}`),
    onremove: () => clearInterval(timer),
  };
}

Component composition

Props

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import { Component, NgModule } from "@angular/core";
import { UserprofileModule } from "./userprofile.component";

@Component({
  selector: "app-root",
  template: `
    <app-userprofile
      name="John"
      [age]="20"
      [favouriteColors]="['green', 'blue', 'red']"
      [isAvailable]="true"
    >
    </app-userprofile>
  `,
})
export class AppComponent {}

@NgModule({
  declarations: [AppComponent],
  imports: [UserprofileModule],
  bootstrap: [AppComponent],
})
export class AppModule {}

logo of Mithril Mithril

import m from "mithril";
import UserProfile from "./UserProfile.js";

export default function App() {
  return {
    view: () =>
      m(UserProfile, {
        name: "john",
        age: 20,
        favouriteColors: ["green", "blue", "red"],
        isAvailable: true,
      }),
  };
}

Emit to parent

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import { Component, NgModule } from "@angular/core";
import { AnswerButtonModule } from "./answer-button.component";

@Component({
  selector: "app-root",
  template: `
    <p>Are you happy?</p>

    <app-answer-button (yes)="onAnswerYes()" (no)="onAnswerNo()">
    </app-answer-button>

    <p style="font-size: 50px">{{ isHappy ? "😀" : "😥" }}</p>
  `,
})
export class AppComponent {
  isHappy = true;

  onAnswerYes() {
    this.isHappy = true;
  }

  onAnswerNo() {
    this.isHappy = false;
  }
}

@NgModule({
  declarations: [AppComponent],
  imports: [AnswerButtonModule],
  bootstrap: [AppComponent],
})
export class AppModule {}

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import m from "mithril";
export const AnswerButton = ({ attrs: { onYes, onNo } }) => ({
  view: () =>
    m(
      "div",
      m("button", { onclick: onYes }, "YES"),
      m("button", { onclick: onNo }, "NO"),
    ),
});

Slot

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import { Component, NgModule } from "@angular/core";
import { FunnyButtonModule } from "./funny-button.component";

@Component({
  selector: "app-root",
  template: `<app-funny-button>Click me!</app-funny-button>`,
})
export class AppComponent {}

@NgModule({
  declarations: [AppComponent],
  imports: [FunnyButtonModule],
  bootstrap: [AppComponent],
})
export class AppModule {}

logo of Mithril Mithril

import m from "mithril";
import { FunnyButton } from "./FunnyButton.jsx";

export default function App() {
  return {
    view: () => m(FunnyButton, "Click me!"),
  };
}

Slot fallback

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import { Component, NgModule } from "@angular/core";

@Component({
  selector: "app-root",
  template: `
    <app-funny-button></app-funny-button>

    <app-funny-button>
      <ng-template #content>I got content!</ng-template>
    </app-funny-button>
  `,
})
export class AppComponent {}

@NgModule({
  declarations: [AppComponent],
  imports: [FunnyButtonModule],
  bootstrap: [AppComponent],
})
export class AppModule {}

logo of Mithril Mithril

import m from "mithril";
import FunnyButton from "./FunnyButton.jsx";

export default function App() {
  return {
    view: () => m("", m(FunnyButton), m(FunnyButton, "I got Content")),
  };
}

Context

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import { Component, NgModule } from "@angular/core";
import { UserService } from "./user.service";
import { UserProfileModule } from "./user-profile.component";

@Component({
  providers: [UserService],
  selector: "app-root",
  template: `
    <h1>Welcome back, {{ userService.user.username }}</h1>
    <app-user-profile />
  `,
})
export class AppComponent {
  constructor(public userService: UserService) {}
}

@NgModule({
  declarations: [AppComponent],
  imports: [UserProfileModule],
  bootstrap: [AppComponent],
})
export class AppModule {}

logo of Mithril Mithril

import m from "mithril";
import UserProfile from "./UserProfile";

export default function App() {
  const user = {
    id: 1,
    username: "unicorn42",
    email: "[email protected]",
  };

  const updateUsername = (username) => (user.username = username);

  return {
    view: () =>
      m(
        "",
        m("h1", `Welcome Back, ${user.username}`),
        m(UserProfile, { user, updateUsername }),
      ),
  };
}

Form input

Input text

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import { Component, NgModule } from "@angular/core";
import { FormsModule } from "@angular/forms";

@Component({
  selector: "app-input-hello",
  template: `
    <p>{{ text }}</p>
    <input [(ngModel)]="text" />
  `,
})
export class InputHelloComponent {
  text = "";
}

@NgModule({
  declarations: [InputHelloComponent],
  imports: [FormsModule],
  exports: [InputHelloComponent],
})
export class InputHelloModule {}

logo of Mithril Mithril

import m from "mithril";

export default function InputHello() {
  let text = "Hello world";
  const handleChange = ({ target: { value } }) => (text = value);

  return {
    view: () =>
      m("", m("p", text), m("input", { value: text, onchange: handleChange })),
  };
}

Checkbox

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import { Component, NgModule } from "@angular/core";
import { FormsModule } from "@angular/forms";

@Component({
  selector: "app-is-available",
  template: `
    <input id="is-available" type="checkbox" [(ngModel)]="isAvailable" />
    <label for="is-available">Is available</label>
  `,
})
export class IsAvailableComponent {
  isAvailable = false;
}

@NgModule({
  declarations: [IsAvailableComponent],
  imports: [FormsModule],
  exports: [IsAvailableComponent],
})
export class IsAvailableModule {}

logo of Mithril Mithril

import m from "mithril";

export default function IsAvailable() {
  let isAvailable = false;
  const onUpdate = () => (isAvailable = !isAvailable);

  return {
    view: () =>
      m(
        "",

        m("input", {
          id: "is-available",
          type: "checkbox",
          checked: isAvailable,
          onchange: onUpdate,
        }),
        m("label", { for: "is-available" }, "Is available"),
      ),
  };
}

Radio

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import { Component, NgModule } from "@angular/core";
import { FormsModule } from "@angular/forms";

@Component({
  selector: "app-pick-pill",
  template: `
    <div>Picked: {{ picked }}</div>

    <input id="blue-pill" type="radio" value="blue" [(ngModel)]="picked" />
    <label for="blue-pill">Blue pill</label>

    <input id="red-pill" type="radio" value="red" [(ngModel)]="picked" />
    <label for="red-pill">Red pill</label>
  `,
})
export class PickPillComponent {
  picked = "red";
}

@NgModule({
  declarations: [PickPillComponent],
  imports: [FormsModule],
  exports: [PickPillComponent],
})
export class PickPillModule {}

logo of Mithril Mithril

import m from "mithril";

export default function PickPill() {
  let picked = "red";
  let pills = ["red", "green", "blue"];
  const handleChange = ({ target: { value } }) => (picked = value);

  return {
    view: () =>
      m(
        "",
        m("", `Picked: ${picked}`),
        pills.map((pill) =>
          m(
            ".",
            m("input", {
              id: pill,
              checked: picked == pill,
              type: "radio",
              value: pill,
              onchange: handleChange,
            }),
            m("label", { for: pill }, pill),
          ),
        ),
      ),
  };
}

Select

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import { Component, NgModule } from "@angular/core";
import { FormsModule } from "@angular/forms";

@Component({
  selector: "app-color-select",
  template: `
    <select [(ngModel)]="selectedColorId">
      <option
        *ngFor="let color of colors"
        [value]="color.id"
        [disabled]="color.isDisabled"
      >
        {{ color.text }}
      </option>
    </select>
  `,
})
export class ColorSelectComponent {
  selectedColorId = 2;

  colors = [
    { id: 1, text: "red" },
    { id: 2, text: "blue" },
    { id: 3, text: "green" },
    { id: 4, text: "gray", isDisabled: true },
  ];
}

@NgModule({
  declarations: [ColorSelectComponent],
  imports: [FormsModule],
  exports: [ColorSelectComponent],
})
export class ColorSelectModule {}

logo of Mithril Mithril

import m from "mithril";
const colors = [
  { id: 1, text: "red" },
  { id: 2, text: "blue" },
  { id: 3, text: "green" },
  { id: 4, text: "gray", isDisabled: true },
];

export default function ColorSelect() {
  let selectedColorId = 2;

  const handleSelect = ({ target: { value } }) => (selectedColorId = value);

  return {
    view: () =>
      m(
        "select",
        { value: selectedColorId, onchange: handleSelect },
        colors.map(({ id, text, isDisabled }) =>
          m("option", { key: id, id, disabled: isDisabled, value: id }, text),
        ),
      ),
  };
}

Webapp features

Render app

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<!doctype html>
<html>
  <body>
    <app-root></app-root>
  </body>
</html>

logo of Mithril Mithril

<!doctype html>
<html>
  <body>
    <div id="app"></div>
    <script type="module" src="./main.jsx"></script>
  </body>
</html>

Fetch data

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import { HttpClient } from "@angular/common/http";
import { Injectable } from "@angular/core";
import { BehaviorSubject } from "rxjs";

export interface UsersState {
  users: User[];
  error: string | null;
  loading: boolean;
}

export const initialState: UsersState = {
  users: [],
  error: null,
  loading: false,
};

@Injectable({ providedIn: "root" })
export class UserService {
  private state = new BehaviorSubject<UsersState>(initialState);
  state$ = this.state.asObservable();

  constructor(private http: HttpClient) {}

  loadUsers() {
    this.state.next({ ...initialState, loading: true });

    this.http
      .get<UserResponse>("https://randomuser.me/api/?results=3")
      .subscribe({
        next: ({ results }) =>
          this.state.next({ ...initialState, users: results }),
        error: (error) => this.state.next({ ...initialState, error }),
      });
  }
}

export interface UserResponse {
  results: User[];
  info: any;
}

export interface User {
  name: {
    title: string;
    first: string;
    last: string;
  };
  picture: {
    large: string;
    medium: string;
    thumbnail: string;
  };
}

logo of Mithril Mithril

import m from "mithril";

export default function App() {
  let isLoading = false;
  let error = null;
  let users = [];

  async function fetchUsers() {
    isLoading = true;
    try {
      const { results } = await m.request(
        "https://randomuser.me/api/?results=3",
      );
      users = results;
    } catch (err) {
      error = err;
    }
    isLoading = false;
  }

  return {
    oninit: fetchUsers,
    view() {
      if (isLoading) return m("p", "Fetching users...");
      if (error) return m("p", "An error occurred while fetching users");
      return users.map((user) =>
        m(
          "li",
          { key: user.login.uuid },
          m("img", { src: user.picture.thumbnail, alt: "user" }),
          m("p", `${user.name.first} ${user.name.last}`),
        ),
      );
    },
  };
}