element-f

Define your custom elements with elegance 👒

Installation

npm i element-f

Basics

In order to define a custom-element, you only need one definition function:

import elementF from "element-f";

const MyElement = elementF(function(){
  // Your logic goes here  
  const shadow = this.attachShadow({mode: 'open'});
});

To tap into lifecycle events, this function can use the "life" event emitter:

const MyElement = elementF(function(life)=> {
    const shadow = this.attachShadow({mode: 'open'});
    // Listen once to when this component connects to a document 
    life.once('connect', ()=> shadow.innerHTML = `I'm Alive!`);
});

The "life" event emitter supports three methods:

• once(name, fn)
on(name, fn) - Registers fn for events of name name. once() will invoke fn once.
  • name - The name of the event to listen to
  • fn(payload) - The function to be called when an event occurs
    • payload - An object containing information regarding the event
• off(name, fn) - Removes an event handler previously registered using on or once.

The following events are thrown:

• connect - Fired upon connectedCallback. Delivers no payload.
• disconnect - Fired upon disconnectedCallback. Delivers no payload.
• attribute:[Attribute Name] - Fired when an observed attribute changes. Delivers previousValue and newValue as payload.

To observe attributes, just add their list to elementF call:

const MyElement = elementF(function(life)=> {
    life.on('attribute:foo', ({ previousValue, newValue })=> {
        // Do something when attribute "foo" changes value
    });

    life.on('attribute:bar', ({ previousValue, newValue })=> {
        // Do something when attribute "bar" changes value
    });
}, ["foo", "bar"]);

Usage Examples

Whereas defining custom elements using standard class notation looks like this:

class MyButton extends HTMLElement {
    
    constructor(){
      super();
      console.log(`I'm alive!`);
    }

    static get observedAttributes(){
        return ['disabled'];
    }
    
    attributeChangedCallback(name, oldValue, newValue) {
      if(name === "disabled") this.classList.toggle('disabled', newValue);
    }

    connectCallback() {
      this.innerHTML = "<b>I'm an x-foo-with-markup!</b>";
    }
}

With element-f the same custom element definition would look like this:

const MyButton = elementF(function(life)=> {

  console.log(`I'm alive!`);
  life.on('connect', ()=> this.innerHTML = "<b>I'm an x-foo-with-markup!</b>");
  life.on('attribute:disabled', ({ newValue, oldValue })=> this.classList.toggle('disabled', newValue));

}, ['disabled']);

Compact, functional and elegant 😇

What does Element-F solve?

Element-F is a stylistic framework, not a fundamental solution to any specific architectural or functional problem. If you're happy with OOP-styled constructs, you probably wouldn't draw much enjoyment from using it :)