Reactivity
Declare state
Update state
Mithril
import m from "mithril";
export default function Name() {
let name = "John";
name = "Jane";
return {
view: () => m("h1", `Hello ${name}`),
};
}
Computed state
Mithril
import m from "mithril";
export default function DoubleCount() {
let count = 10;
let doubleCount = count * 2;
return {
view: () => m("div", doubleCount),
};
}
Templating
Minimal template
Styling
Mithril
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
Mithril
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
Mithril
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
Mithril
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
Mithril
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())),
),
};
}
import { track } from "ripple";
const TRAFFIC_LIGHTS = ["red", "orange", "green"];
export default function TrafficLight() {
let &[lightIndex] = track(0);
let &[light] = track(() => TRAFFIC_LIGHTS[lightIndex]);
function nextLight() {
lightIndex = (lightIndex + 1) % TRAFFIC_LIGHTS.length;
}
return <>
<button onClick={nextLight}>"Next light"</button>
<p>"Light is "{light}</p>
<p>
"You must "
if (light === "red") {
<span>"STOP"</span>
} else if (light === "orange") {
<span>"SLOW DOWN"</span>
} else if (light === "green") {
<span>"GO"</span>
}
</p>
</>;
}
Lifecycle
On mount
Mithril
import m from "mithril";
export default function PageTitle() {
return {
view: () => m("p", `Page title: ${document.title}`),
};
}
On unmount
Mithril
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),
};
}
import { effect, track } from "ripple";
export default function Time() {
let &[time] = track(new Date().toLocaleTimeString());
effect(() => {
const timer = setInterval(() => {
time = new Date().toLocaleTimeString();
}, 1000);
return () => clearInterval(timer);
});
return <h1>"Current time: "{time}</h1>;
}
Component composition
Props
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
Mithril
import m from "mithril";
export const AnswerButton = ({ attrs: { onYes, onNo } }) => ({
view: () =>
m(
"div",
m("button", { onclick: onYes }, "YES"),
m("button", { onclick: onNo }, "NO"),
),
});
import { track } from "ripple";
import { AnswerButton } from "./AnswerButton.tsrx";
export function App() {
let &[isHappy] = track(true);
function onAnswerNo() {
isHappy = false;
}
function onAnswerYes() {
isHappy = true;
}
return <>
<p>"Are you happy?"</p>
<AnswerButton onYes={onAnswerYes} onNo={onAnswerNo} />
<p style={{ fontSize: "50px" }}>{isHappy ? "😀" : "😥"}</p>
</>;
}
Slot
Slot fallback
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
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 }),
),
};
}
import { RippleObject } from "ripple";
import { UserContext } from "./UserContext.tsrx";
import { UserProfile } from "./UserProfile.tsrx";
export function App() {
const user = new RippleObject({
id: 1,
username: "unicorn42",
email: "[email protected]",
});
UserContext.set(user);
return <>
<h1>"Welcome back, "{user.username}</h1>
<UserProfile />
</>;
}
Form input
Input text
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
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
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),
),
),
),
};
}
import { bindGroup, track } from "ripple";
export default function PickPill() {
let &[picked, pickedTracked] = track("red");
return <>
<div>"Picked: "{picked}</div>
<input
id="blue-pill"
type="radio"
value="blue"
ref={bindGroup(pickedTracked)}
/>
<label for="blue-pill">"Blue pill"</label>
<input
id="red-pill"
type="radio"
value="red"
ref={bindGroup(pickedTracked)}
/>
<label for="red-pill">"Red pill"</label>
</>;
}
Select
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),
),
),
};
}
import { bindValue, track } from "ripple";
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, selectedColorIdTracked] = track(2);
return <select ref={bindValue(selectedColorIdTracked)}>
for (const color of colors; key color.id) {
<option value={color.id} disabled={color.isDisabled}>
{color.text}
</option>
}
</select>;
}
Webapp features
Render app
Mithril
<!doctype html>
<html>
<body>
<div id="app"></div>
<script type="module" src="./main.jsx"></script>
</body>
</html>
Ripple
<!doctype html>
<html>
<body>
<div id="app"></div>
<script type="module" src="./main.js"></script>
</body>
</html>
Fetch data
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}`),
),
);
},
};
}
import { useFetchUsers } from "./useFetchUsers.tsrx";
export function App() {
const data = useFetchUsers();
return <>
if (data.isLoading) {
<p>"Fetching users..."</p>
} else if (data.error) {
<p>"An error occurred while fetching users"</p>
} else if (data.users) {
<ul>
for (const user of data.users; key user.login.uuid) {
<li>
<img src={user.picture.thumbnail} alt="user" />
<p>{user.name.first}" "{user.name.last}</p>
</li>
}
</ul>
}
</>;
}