Frontend Overview: Vanilla JS + Bootstrap 5 Interface

The Factus Challenge frontend lives in the fr-v1/ directory and is a fully static HTML application built with ES modules. There is no build step, no bundler, and no framework — you can open index.html directly in a browser or serve the folder from any static host. All JavaScript is loaded as native ES modules via <script type="module">, and each page controller is a class of pure static methods.

Technology Stack

HTML5 + Bootstrap 5.3.3

Uses the Bootstrap 5.3.3 Vapor dark theme, loaded from resources/utils/bootstrap-5.3.3/. The entire layout relies on Bootstrap utility classes — no custom CSS grid.

Vanilla JS ES Modules

All logic lives in .mjs files under resources/js/. Each view is an exported default class with only static methods; the classes throw on construction.

Tabulator 6.3

Tabulator 6.3 powers every data table. Progressive-scroll loading, column tooltips, custom cell formatters, and footer action buttons are used throughout.

Luxon 3

Luxon 3 handles all date parsing and formatting. Dates from the API arrive as dd-MM-yyyy hh:mm:ss a and are displayed in a long Spanish locale format.

Additional bundled libraries:

Bootstrap Popper (resources/utils/popper/) — powers dropdowns and tooltips
Custom utilities in resources/utils/own/:
- helpers.js — Helpers class
- toast.js — Toast class
- popup.js — Popup / Modal class
- icons.js — icons object of SVG strings
- dialog.js — base Dialog class extended by Popup

Directory Structure

fr-v1/
├── index.html                  # SPA shell — loads navigation and router (index.mjs)
├── favicon.ico
├── pages/                      # Standalone HTML pages (each reuses the same shell layout)
│   ├── about.html
│   ├── cliente.html
│   ├── factus.html
│   └── factusget.html
└── resources/
    ├── assets/
    │   ├── config.json         # Backend URL configuration (single field: "url")
    │   └── ciudades.json       # Municipality data (fallback / static reference)
    ├── css/
    │   └── styles.css          # Custom styles on top of Bootstrap Vapor
    ├── html/                   # Partial HTML templates loaded dynamically by JS modules
    │   ├── about.html
    │   ├── clientes.html
    │   ├── factus.html
    │   ├── inicio.html
    │   ├── productos.html
    │   └── search_factus.html
    ├── js/                     # ES module page controllers
    │   ├── index.mjs           # App bootstrap + router
    │   ├── inicio.mjs          # Home page
    │   ├── factus.mjs          # Invoices CRUD (Factus class)
    │   ├── clientes.mjs        # Clients CRUD (Clientes class)
    │   ├── factusearch.mjs     # Invoice search + PDF download (FactuSearch class)
    │   ├── about.mjs           # About page (About class)
    │   └── customs.mjs         # Shared UI utilities (exported functions)
    └── utils/                  # Vendor libs + custom utilities
        ├── bootstrap-5.3.3/
        ├── tabulator-6.3/
        ├── luxon3x.min.js
        ├── popper/
        └── own/
            ├── helpers.js
            ├── toast.js
            ├── popup.js
            ├── dialog.js
            └── icons.js

Configuration

The only thing you need to change to point the frontend at a different backend is the single-field config.json file. On startup, index.mjs fetches this file and writes the URL to window.urlAPI, which every module then reads as a global.

resources/assets/config.json

{
  "url": "http://localhost:4500"
}

Change url to the address of your deployed backend (e.g. https://api.myserver.com) and the entire frontend will switch targets without any other modification.

How the Router Works

index.mjs defines a single App class. When the page loads, App.main():

Fetch config

Reads config.json and stores config.url in window.urlAPI. Also registers shared globals (window.Tabulator, window.Toast, window.Modal, window.Helpers, window.icons, window.DateTime, etc.).

Verify backend connection

Calls GET ${urlAPI}/. If the response status is 200 the router continues; otherwise a danger Toast is shown.

Read current page

Extracts the trailing filename from window.location.href using the regex /[^/]+\.html$/ — e.g. factus.html.

Dynamic import

Passes the filename to App.#mainMenu(option), which uses a switch statement to dynamically import() the matching .mjs module and calls its .init() static method.

resources/js/index.mjs (router excerpt)

switch (option) {
  case 'index.html':
    App.#loadHome()
    break
  case 'factus.html':
    const { default: Factus } = await import('./factus.mjs')
    Factus.init()
    break
  case 'cliente.html':
    const { default: Clientes } = await import('./clientes.mjs')
    Clientes.init()
    break
  case 'about.html':
    const { default: About } = await import('./about.mjs')
    About.init()
    break
  case 'factusget.html':
    const { default: FactuSearch } = await import('./factusearch.mjs')
    FactuSearch.init()
    break
}

Custom Utility Classes

All utility classes are exposed as window globals by index.mjs so every lazily-loaded module can use them without additional imports.

Helpers — HTTP fetching and form validation

Defined in resources/utils/own/helpers.js. Exposes common operations needed by all page controllers.

Method	Signature	Description
`fetchJSON`	`fetchJSON(url, data?)`	Wraps `fetch`, auto-serialises an `Object` body to JSON, returns parsed JSON. Always resolves (errors returned as plain objects).
`fetchText`	`fetchText(url, container?)`	Fetches an HTML partial. If `container` (CSS selector) is provided, injects the HTML there; otherwise returns the raw string.
`toOptionList`	`toOptionList({ items, value, text, selected?, firstOption? })`	Builds a string of `<option>` elements from an array of objects. Used to populate every `<select>` in the app.
`okForm`	`okForm(formSelector, callBack?)`	Triggers native HTML5 form validation; returns `true` if valid. Accepts an optional extra validation callback.
`selectOptionByText`	`selectOptionByText(select, text)`	Finds and selects a `<select>` option by its visible text — used when pre-filling edit forms.
`idRandom`	`idRandom(prefix?)`	Returns a zero-padded 14-digit random numeric string (used for unique modal/popover IDs).
`flat` / `flatten`	`flat(data)` / `flatten(obj, final?)`	Recursively flattens nested objects — useful for working with joined API responses.

// Example: populating a select from the API
const response = await Helpers.fetchJSON(`${urlAPI}/get-data/payment_method`)
const options = Helpers.toOptionList({
  items: response.data,
  value: 'id',
  text: 'name',
  firstOption: 'Seleccione un método de pago',
})
document.querySelector('#pago').innerHTML = options

Toast — Bootstrap toast notifications

Defined in resources/utils/own/toast.js. Displays a slide-in notification anchored to a <dialog> element appended to <body>.

Toast.show({
  title: 'Sistema de ventas',       // optional header text
  message: 'Cliente creado',        // supports HTML
  mode: 'success',                  // 'info' | 'success' | 'warning' | 'danger'
  duration: 3000,                   // auto-dismiss after N ms (default 3000)
  error: someError,                 // if provided, also logs to console.error
})

Each mode maps to a Bootstrap icon: checkCircleFill (success), infoCircleFill (info), exclamationCircleFill2 (warning), xCircleFill (danger).

Modal (Popup) — Bootstrap-style dialog

Defined in resources/utils/own/popup.js, extends the base Dialog class in dialog.js. Used for all CRUD forms.

const modal = new Modal({
  modal: false,          // always effectively false — Dialog base class forces non-blocking .show()
  classes: Customs.classesModal, // CSS classes for positioning/sizing
  title: '<h5>Ingreso de clientes</h5>',
  content: htmlString,   // raw HTML injected into the dialog body
  buttons: [
    { caption: addButton, classes: 'btn btn-primary me-2', action: () => handleAdd() },
    { caption: cancelButton, classes: 'btn btn-secondary', action: () => modal.remove() },
  ],
  doSomething: (idModal) => populateForm(idModal), // callback fired after render
})
modal.show() // returns a Promise that resolves with the clicked button text

The doSomething callback receives the auto-generated idModal string so downstream code can scope document.querySelector to that specific modal instance.

The Dialog base class always sets this.modal = false regardless of the value passed to the constructor, so the native <dialog>.showModal() path is never taken. Every Modal instance uses non-blocking .show() and relies on the blur filter applied to the rest of the page body.

Customs — Shared UI helpers

Defined in resources/js/customs.mjs. Exported as named exports, re-exposed globally as window.Customs.

Export	Description
`classesModal`	Standard CSS class string applied to every `Modal` — `'position-absolute top-50 start-50 translate-middle bg-dark col-12 col-sm-10 col-md-9 col-lg-8 col-xl-7'`
`showInfoAboutUse(section)`	Shows a usage hint Toast on first/second visit to a section, tracked via `localStorage`.
`toastBeforeAddRecord(msg?, just?)`	Shows a warning Toast when a form is submitted while invalid.
`popover(title, html, buttons, classPop?)`	Creates and appends a native `popover` element to `<body>` with a header, content area, and footer buttons.
`showPopover(pop)`	Calls `pop.showPopover()` and blurs the rest of the page body (`filter: blur(2px)`).
`closePopover(pop)`	Removes the popover element and clears the blur effect.
`new_client()`	Opens `pages/cliente.html` in a new tab — triggered from within the invoice creation form to allow adding a customer on the fly.

Icons — SVG string constants

Defined in resources/utils/own/icons.js. A plain export default object where each key is a descriptive name and each value is an SVG string. Used inline in button HTML. Exposed as window.icons.Key icons used by the UI: icons.plusSquare (add row), icons.edit (edit row), icons.delete (delete row), icons.deleteWhite / icons.editWhite (modal submit buttons), icons.xLg (cancel), icons.pdf_icon1 (PDF download).

Get Started

Backend

Frontend

Deployment

Frontend Overview: Vanilla JS + Bootstrap 5 Interface

Technology Stack

HTML5 + Bootstrap 5.3.3

Vanilla JS ES Modules

Tabulator 6.3

Luxon 3

Directory Structure

Configuration

How the Router Works

Custom Utility Classes

Build docs developers (and LLMs) love

Get Started

Backend

Frontend

Deployment

Documentation Index

​Technology Stack

HTML5 + Bootstrap 5.3.3

Vanilla JS ES Modules

Tabulator 6.3

Luxon 3

​Directory Structure

​Configuration

​How the Router Works

​Custom Utility Classes

Build docs developers (and LLMs) love

Technology Stack

Directory Structure

Configuration

How the Router Works

Custom Utility Classes