@erickmerchant/framework

A simple frontend framework.

Get started

import {
  cache
  createApp,
  html,
} from 'https://cdn.skypack.dev/@erickmerchant/framework?min'

const app = createApp({items: []})

createApp takes the initial state of the app. It can be any type, but an object usually makes sense.

Rendering some html

const target = document.querySelector('#app');

const cls = getCls();

const view = (state) => html`
  <div id="app" class=${cls} />
`;

app.render(view, target);

This doesn't do much right now, but it does demonstrate a few things.

• How to render an element with no children. The self closing /> is required even on tags that normally wouldn't need it and it's allowed on all, even those that normally wouldn't allow it.
• How to render static attributes. id="app" is static. It will be the same each time this view is rendered. The quotes (single or double) are require.
• How to render cached attributes. class=${cls} is cached. Its value is not hard-coded. However every time the view is rendered it will not change, even if getCls() returns a new value.

Dynamic children

const view = (state) => html`
  <div id="app">
    <ol>
      ${state.items.map(
        (item) =>
          html`
            <li>${item}</li>
          `
      )}
    </ol>
  </div>
`;

This shows how you can have dynamic children and how you'd output an array of items.

Cached children

Sometimes you'll have some html that needs to be dynamic once but after that can be treated as if it were static. That's where cache comes into play.

const title = 'The heading';

const heading = cache(
  html`
    <h1>${title}</h1>
  `
);

const view = (state) => html`
  <div id="app">
    ${heading}
    <ol>
      ${state.items.map(
        (item) =>
          html`
            <li>${item}</li>
          `
      )}
    </ol>
  </div>
`;

Properties

Cached attributes are useful, but often you'll have attributes that need to change. This is where you can use properties instead. Properties are always reevaluated. You can indicate a property with :, a single colon.

Please note that class will get expanded to className and for will get expanded to htmlFor.

let hasFoo = true;

let barValue = "I'm the bar value";

const view = (state) => html`
  <form id="app">
    <label>
      Has foo
      <input type="checkbox" :checkbox=${hasFoo} />
    </label>
    <label>
      Bar value
      <input type="text" :value=${barValue} />
    </label>
  </form>
`;

Also worth pointing out in this example is that hasFoo is a boolean, which demonstrates how to render boolean properties.

Events

const onClick = (e) => {
  e.preventDefault();
};

const view = (state) => html`
  <div id="app">
    <button @click=${onClick}>Click here</button>
  </div>
`;

The framework always uses event delegation. For instance with this click handler above a single event handler is added to the document with capture set to true. When a click occurs the target is checked to see if it was registered as having a handler. If it was then the handler is called with the event object.

Changing state

const onClick = (e) => {
  e.preventDefault();

  app.state = {count: app.state.count + 1};
};

const view = (state) => html`
  <div id="app">
    <p>${state.count}</p>
    <button @click=${onClick}>Click here</button>
  </div>
`;

Server-side rendering

import {stringify, html} from '@erickmerchant/framework/stringify.js';

const view = (state) => html`
  <div id="app">
    <ol>
      ${state.items.map(
        (item) =>
          html`
            <li>${item}</li>
          `
      )}
    </ol>
  </div>
`;

const staticHTML = stringify(view({items}));

res.write(staticHTML);