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GitHub - matthewp/haunted: React's Hooks API implemented for web compone...

 5 years ago
source link: https://github.com/matthewp/haunted
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readme.md

Haunted ??

React's Hook API but for standard web components and lit-html.

<!doctype html>

<my-counter></my-counter>


<script type="module">
  import { html } from 'https://unpkg.com/lit-html/lit-html.js';
  import { component, useState } from 'https://unpkg.com/@matthewp/haunted/haunted.js';

  function Counter() {
    const [count, setCount] = useState(0);

    return html`
      <div id="count">${count}</div>
      <button type="button" @click=${() => setCount(count + 1)}>Increment</button>
    `;
  }

  customElements.define('my-counter', component(Counter));
</script>

Install

For now it is available as the @matthewp/haunted package. In the future I hope to get the non-scoped name.

npm install @matthewp/haunted

API

Haunted supports the same API as React Hooks. My hope is that by doing so you can reuse hooks available on npm simply by aliasing package names in your bundler's config.

Currently Haunted supports the following hooks:

useState

Create a tuple of state and a function to change that state.

const [count, setCount] = useState(0);

useEffect

Useful for side-effects that run after the render has been commited.

<!doctype html>

<my-counter></my-counter>

<script type="module">
  import { html } from 'https://unpkg.com/lit-html/lit-html.js';
  import { component, useState, useEffect } from 'https://unpkg.com/@matthewp/haunted/haunted.js';

  function Counter() {
    const [count, setCount] = useState(0);

    useEffect(() => {
      document.title = `Clicked ${count} times`;
    });

    return html`
      <div id="count">${count}</div>
      <button type="button" @click=${() => setCount(count + 1)}>Increment</button>
    `;
  }

  customElements.define('my-counter', component(Counter));
</script>

useReducer

Create state that updates after being ran through a reducer function.

<!doctype html>

<my-counter></my-counter>


<script type="module">
  import { html } from 'https://unpkg.com/lit-html/lit-html.js';
  import { component, useReducer } from 'https://unpkg.com/@matthewp/haunted/haunted.js';

  const initialState = {count: 0};

  function reducer(state, action) {
    switch (action.type) {
      case 'reset': return initialState;
      case 'increment': return {count: state.count + 1};
      case 'decrement': return {count: state.count - 1};
    }
  }

  function Counter() {
    const [state, dispatch] = useReducer(reducer, initialState);

    return html`
      Count: ${state.count}
      <button @click=${() => dispatch({type: 'reset'})}>
        Reset
      </button>
      <button @click=${() => dispatch({type: 'increment'})}>+</button>
      <button @click=${() => dispatch({type: 'decrement'})}>-</button>
    `;
  }

  customElements.define('my-counter', component(Counter));
</script>

useMemo

Create a memoized state value. Only reruns the function when dependent values have changed.

<!doctype html>

<my-app></my-app>

<script type="module">
  import { html } from 'https://unpkg.com/lit-html/lit-html.js';
  import { component, useMemo, useState } from 'https://unpkg.com/@matthewp/haunted/haunted.js';

  function fibonacci(num) {
    if (num <= 1) return 1;

    return fibonacci(num - 1) + fibonacci(num - 2);
  }

  function App() {
    const [value, setVal] = useState(12);
    const fib = useMemo(() => fibonacci(value), [value]);

    return html`
      <h1>Fibonacci</h1>
      <input type="text" @change=${ev => setVal(Number(ev.target.value))} value="${value}">
      <div>Fibonacci <strong>${fib}</strong></div>
    `;
  }

  customElements.define('my-app', component(App));
</script>

License

BSD-2-Clause


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