Component (@veams/component)

Component Class for Components which can be used in static page projects in VEAMS.

---

Features

The class provides a base system to build components. It merges options, bind and unbind events without worrying about that, subscribe to global events and renders templates with data.

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Installation

NPM

npm install @veams/component --save

Yarn

yarn add @veams/component

---

Usage

Initial methods

constructor(obj, options)

• default options are defined here
• you have to call super(obj, options) to merge default with markup options

initialize(...args)

• called in the constructor
• useful for preparing your component, but cannot use any defined class property
• gets the object and markup options objects as parameters

create()

• This function just executes other functions and will be executed by @veams/plugin-modules.
• When you want to use a component in another component, call the function after init.

preRender()

• if needed templates can be pre-rendered here using renderTemplate (see section "Render templates")

bindEvents()

• bind events manually here using registerEvent (see section "Events / Manual binding")

render()

• called as long as option render is not set to false in options of module loader
• render your templates here or update the state of your component

Lifecycle hooks

The VeamsComponent provides useful lifecycle hooks.

willMount()

• executed after initialize

didMount()

• executed after initial render

willUnmount()

• executed before unregistering events

didUnmount()

• executed after unregistering events

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Merging options

• default options defined in constructor will be merged with markup options by calling super(obj, options) in constructor
• markup options have higher priority and always overwrite default options properties of the same name

Example for overwriting default options with markup options:

<div
    data-js-module="slider"
    data-js-options='{
        "infinite": true,
        "pauseOnHover": false}'
>...</div>

---

Provided parameters

When the component gets initialized, it expects to get passed two parameters:

1. obj - Generic Object which contains
   • el - Required: Node/element which is associated with it.
   • namespace - Optional: Namespace which is associated with the module.
   • options - Optional: Options object.
   • context - Optional: The context object is your custom Veams object.
2. options - Optional: Markup Options which are read out by this plugin

---

Event Handling

subscribe

The Component Class can subscribe to global events using the getter subscribe. Global events can be triggered with Veams.Vent.trigger('eventName').

Example for global event subscription:

get subscribe() {
	return {
		'\{{Veams.EVENTS.resize}}': 'onResize'
	};
}

events

Local events can be bound by using the getter events.

This package has its own event-handler process and is similar to @veams/query. That means every event handled by a function can provides to the function two paramaters:

1. e - Native event object.
2. target - Target on which you have clicked.

Example 1 (without event delegation)

get events() {
	return {
		'click': 'onClick'
	};
}

In this case the event listener is bound to this.el and executed as soon as the element itself or any of its children is clicked.

Example 2 (with event delegation)

get events() {
	return {
		'click \{{this.options.specialBtn}}': 'onClick'
	};
}

In this case the event listener is also bound to this.el but only executed when the element is clicked which is predefined as specialBtn in options.

Manual event binding with registerEvent()

Sometimes you need to bind events conditionally. Using the provided registerEvent method is a comfortable way.

Example of manually registering local event in automatically called bindEvents

bindEvents() {
	...

	if (condition) {
	
		// register global event
		this.registerEvent('\{{this.options.globalEvent}}', 'eventHandler', true);
	
		// register local event with event delegation
		this.registerEvent('\{{Veams.EVENTS.keydown}} \{{this.options.someSubComponent}}', 'onKeydown');
	}
	
	...
}

---

Render templates with renderTemplate()

Rendering templates with VEAMS is pretty easy. You only have to specify the names of templates you want to use in the options of your component and then make a call to the renderTemplate function, passing the template name and the data as parameters.

render() {

	// render template with provided data
	let tmpl = this.renderTemplate('btn', this.data);

	// append output to current element
	this.$el.append(tmpl);
}

---

Auto Creation

You are able to auto create your component by using the provided method autocreate(). The method returns the instance and executes all important lifecycle methods for you.

import Component, { autocreate } from '@veams/component';
import Veams from './app.veams'
import Counter from './counter';

const counter = autocreate()(new Counter({
	el: document.getElementById('counter')
}));

Veams.onDOMReady(() => {
	counter.render();
});

---

Example

import $ from 'jquery';
import Component from '@veams/component';

class Comparer extends Component {
	/**
	 * Constructor for our class
	 *
	 * @see module.js
	 *
	 * @param {Object} obj - Object which is passed to our class
	 * @param {Object} obj.el - element which will be saved in this.el
	 * @param {Object} obj.options - options which will be passed in as JSON object
	 */
	constructor(obj) {
		let options = {
			handle: '[data-js-item="comparer-handle"]',
			topContainer: '[data-js-item="comparer-top-container"]',
			topContent: '[data-js-item="comparer-top-content"]',
			draggClass: 'is-dragging',
			dragMode: true,
			topContentRight: false,
			disabled: {
				'desktop': false,
				'tablet-large': false,
				'tablet-small': false,
				'mobile-large': false,
				'mobile-medium': false,
				'mobile-small': false
			}
		};

		super(obj, options);
		
		this.$el = $(this.el);
	}

	/** =================================================
	 * EVENTS
	 * ================================================ */

	/**
	 * Subscribe to global events of Veams or App namespace.
	 */
	get subscribe() {
		return {
			'{{Veams.EVENTS.resize}}': 'preRender',
			'{{Veams.EVENTS.mediachange}}': 'render'
		};
	}

	/**
	 * Bind local events to this.$el.
	 */
	get events() {
		return {
			'mousedown {{this.options.handle}}': 'mouseDown',
			'mouseup': 'mouseUp',
			'touchstart {{this.options.handle}}': 'mouseDown',
			'touchend': 'mouseUp',
			'mousemove': 'resizeContainer'
		};
	}

	/** =================================================
	 * STANDARD METHODS
	 * ================================================= */

	/**
	 * Initialize the view and merge options
	 *
	 */
	initialize() {
		...
	}


	/**
	 * Pre-Render method
	 */
	preRender(){
		...
	}

	/**
	 * Render method
	 */
	render() {
		...
	}

	/** =================================================
	 * CUSTOM METHODS
	 * ================================================= */

	mouseDown(e) {
		...
	}

	mouseUp() {
	    ...
	}
	
	resizeContainer(e) {
		...
	}
}

export default Comparer;