@soil/arch

Architectural constructs for web applications.

Documentation

element() (function)

Components are the main building block of modern web applications. They are functions responsible for creating instances of custom elements, which typically are regular HTML or SVG elements extended with custom functions, getters and setters. The element() function facilitates and streamlines the creation of such components, in a way that makes them resemble native elements.

element() accepts a function which serves as the definition of the custom component. In turn, that function is responsible for returning a two-size tuple containing the internal DOM structure of the element (its "template") and a number of functions which will determine the ways one is allowed to interact with it (its "controller"), and optionally accepts a series of children.

import {element} from '@soil/arch'
import {h} from '@soil/dom'

const fancyLink = element(() => {
    const tmpl = h.a({href: 'https://example.org/'}, ['Fancy Link'])

    const ctrl = {
        set secret(s: number) {
            tmpl.dataset.secret = '' + s
        },
        fly: () => console.log('Taking off...')
    }

    return [tmpl, ctrl]
})

const aFancyLink = fancyLink({secret: 1, className: 'a-fancy-link'})
aFancyLink.secret = 2
aFancyLink.fly()

Note how the controller implement the interface of the properties supported by the component. Following from this, there is no need to perform an initial assignment of the properties to the internal DOM elements: this will happen automatically, enforcing consistent behaviour between initialization and later usage, as we are accustomed to with native interfaces.

Dependencies

When components need dependencies, they can be defined as a high-order function. To facilitate both regular development and testing, both the factory function and the default instance can be exported.

import {element} from '@soil/arch'
import {h} from '@soil/dom'
import {serviceX, ServiceX} from './ServiceX'

export const elemXFactory = (serviceX: ServiceX) => element(() => {
   // ...
})

export const elemX = elemXFactory(serviceX)

chan() (function)

Components may easily communicate with their parents, children and siblings. However when two components are further away from each other, the communication is more complicated. For this cases, a publish-subscribe pattern can be used, through so-called "channels".

import {chan} from '@soil/arch'

export const randomNumbersChan = chan<number>()

// ...

randomNumbersChan.sub(n => console.log('New random number received:', n))

// ...

randomNumbersChan.pub(Math.random())

assert() (function)

This function provides the basic means to achieve programming by contract.

import {assert, Component} from '@soil/arch'

const counter: Component = (input: {value?: number} = {}) => {
    assert(value > -1, 'Negative values are not allowed.')
    // ...
}

When providing a function as the first argument, its source will be added to the error message to provide the programmer with more context for debugging.

assert(() => 1 > 2) // Error: Assertion was: function () { return 1 > 2; }

Installation

The package is available at npm's registry, so it can be installed via npm or Yarn:

npm i -S @soil/arch
# AKA npm install --save @soil/arch

yarn add @soil/arch

License

This project is licensed under the GNU Affero General Public License.