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Thursday, January 11, 2024

Barcode Scanning for Internet Apps — SitePoint

We created this text in partnership with Pixelverse. Thanks for supporting the companions who make SitePoint attainable.

Barcodes are ubiquitous in nearly any enterprise that offers with bodily objects. Whether or not it’s a parcel going out for supply, serial numbers on gadgets, live performance tickets or receipts, chances are high there’s no less than one barcode concerned.

Desk of Contents

Barcodes on everyday items

Historically, these barcodes have been learn utilizing devoted scanning gear that transmits the barcode worth to an software that consumes it, both by way of a cable connection or a wi-fi hyperlink like Bluetooth. The scanner emulates a keyboard and sends the characters within the barcode as digital key presses.

However today, everyone seems to be carrying a smartphone of their pocket — a high-powered, related computing gadget with a digital camera. Builders can construct apps with a UI tailor-made to their particular use case, scan barcodes utilizing the digital camera and immediately hyperlink it to knowledge within the cloud. Some examples embody:

  • recording that upkeep has occurred on a tool by scanning its serial quantity
  • scanning outbound parcels and marking them as delivered
  • processing returns by scanning a barcode on a return sheet after which scanning the UPC codes on the returned objects
  • validating live performance tickets and marking them as consumed
  • … and far more

To start with, these apps have been carried out as native apps for Android and iOS. With the trendy Internet’s capabilities, these apps can now as an alternative be run on a platform all people is aware of: the net browser.

Introducing STRICH: Barcode Scanning for Internet Apps

STRICH is a JavaScript library that brings real-time 1D/2D barcode scanning to the browser. Behind the strange-sounding identify (Strich is German for “line” or “stroke”, the constructing blocks of barcodes) is a lean library distributed by way of npm — with zero dependencies, permitting for simple integration into any internet app. The built-in scanning UI supplies user-friendly options like digital camera choice, tap-to-focus and flashlight (for low-light circumstances), additional accelerating growth. Typescript bindings can be found, together with well-maintained reference documentation.

All generally used barcode sorts are supported:

  • 1D linear barcodes like EAN/UPC, Code 128, Code 39 and others
  • 2D matrix codes equivalent to QR Code, Information Matrix, Aztec Code and PDF417

STRICH leverages applied sciences like WebGL and WebAssembly to carry out the heavy lifting of processing the digital camera stream and attaining native-like efficiency in finding and decoding barcodes. This enables for extremely environment friendly and dependable scanning of barcodes.

Launched in early 2023, STRICH is a comparatively younger product and below fixed growth. The present focus is on bettering recognition charges for current barcode sorts below troublesome circumstances (uneven lighting, out-of-focus codes, broken codes and many others.), however help for much less widespread barcode sorts equivalent to Micro QR can also be within the works.

Why Barcode Scanning in Internet Apps?

Choosing internet apps as an alternative of native apps provides some distinctive benefits, which we’ll go into now.

Simplify growth by concentrating on a single platform

As an alternative of getting to construct for a number of platforms (iOS and Android, probably Home windows) natively or utilizing a hybrid framework like Ionic/Capacitor or Xamarin, you possibly can simply construct an online app from a single codebase. With not too long ago added and now broadly supported PWA capabilities like Push Notifications and Set up to Residence Display screen, there’s usually no good motive for creating a local app, particularly for in-house apps.

Straightforward distribution: you personal the channel

For those who’re constructing an app to scan barcodes, chances are high you’re constructing an in-house app.
These apps are usually solely utilized by workers, and publishing to Apple’s App Retailer or Google Play is usually a actual trouble:

  • separate distribution channels (Apple App Retailer/Google Play) with their particular person idiosyncrasies, and related prices
  • screenshots and different belongings wanted, in a number of resolutions and languages
  • filling out prolonged privateness questionnaires
  • directions must be offered for reviewers to check the app

The final level specifically is a standard hurdle, as all these apps usually require connectivity to inside backends or authentication credentials that may’t be mocked for testing. Rejected app updates, frequent guide intervention and inexplicable delays in publishing are widespread — to not point out the chance of a business-critical app being faraway from the App Retailer as a result of somebody forgot to behave on an e-mail.

Deployment of a native app vs a web app

Internet apps, as compared, are straightforward to distribute and don’t require specialised Android or iOS sources or personnel. Deploying an online app is often automated utilizing a CI/CD pipeline, with no person interplay or delays concerned. An online app is all the time updated, there’s no assessment course of, and also you’re in full management of the distribution channel.

App fatigue

Going “no app” can also be more and more seen as a optimistic differentiator, as customers have gotten uninterested in putting in apps on their telephone’s crowded house display screen — particularly ones they don’t use each day.

Providing a pleasant browser-based expertise with no additional hoops to leap by way of is appreciated, particularly by tech-savvy of us. And with Progressive Internet Apps (PWAs), you possibly can nonetheless add Set up to Residence Display screen or offline capabilities.

For in-house apps, having a QR code displayed in a outstanding location is a straightforward solution to launch your app, as nearly everyone seems to be aware of the idea of scanning a QR code to open a web site after the pandemic.

Launch web app by scanning QR code

Constructing a Scanning App with STRICH

Constructing an app that scans barcodes may be very straightforward with STRICH. For example, we’ll construct a ticket scanner app.

Acquiring a license key

STRICH requires a sound license key to make use of. To acquire a key, you want to create an account within the Buyer Portal and begin the free trial. You then specify the URLs below which your app is reachable and create the important thing.

Within the instance beneath, we’re including three URLs: one for growth, one for a staging surroundings, and one for manufacturing.

Creating a license key in the Customer Portal

Be aware: apps that require digital camera entry must be served from a safe context, which implies the connection must be safe (HTTPS) or by way of localhost. Instruments like ngrok make this straightforward by mapping an area port to a publicly accessible URL with an mechanically generated TLS certificates. However you don’t want them for those who’re comfy organising certificates your self.

Including the SDK to your app

When you’ve obtained the license key in your app, you possibly can go forward and set up the SDK. For those who’re utilizing npm to handle your dependencies, you need to use npm set up similar to with another dependency:

npm set up @pixelverse/strichjs-sdk

Then, in your software’s startup code, present the license key to the StrichSDK.initialize() methodology:

StrichSDK.initialize('<your license key>')
    .then(() => console.log('STRICH initialized'));

When the promise resolves, the SDK is able to use.

Implementing a scanning use case

Now we will begin implementing the precise barcode scanning move.

For this text, we’ll construct a easy ticket scanner. The app will scan the barcode on a ticket, show the ticket quantity, validity and data on the holder. Trying up the latter would in all probability contain an HTTP request, which we’ll omit for the sake of simplicity.

Selecting a format

Most scanning apps undertake a split-screen format, the place the higher half accommodates the digital camera preview and the decrease half supplies course of context, outcome show and actions. Our ticket scanning app will undertake a format composed of the next parts:

  • Header: Shows a title for steerage.

  • Scanning Space: The place the digital camera feed will likely be proven.

  • Information: The scanned ticket quantity together with the identify and age of the holder, which could have been fetched from a service.

  • Actions: A set of actions to take after scanning a ticket. Actions ought to be situated on the backside of the display screen to offer straightforward thumb entry.

Basic layout of app

With the format in place, we will begin placing collectively some HTML, CSS and JavaScript.

The HTML for the app is proven beneath. I’ve omitted the styling because it‘s not very fascinating. The complete supply code of the instance is out there on GitHub:

<html lang="en">
    <title>Ticket Scanner Instance</title>
    <meta identify="viewport" content material="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
    <header>Ticket Scanner</header>
    <part id="scanner">
    <part id="outcomes">
        <h3>Ticket #</h3>
        <p id="ticket_number">

        <h3>Ticket holder</h3>
        <p id="ticket_holder">
    <part class="actions">
        <button id="deny_button">DENY</button>
        <button id="admit_button">ADMIT</button>

<script kind="module">
   <!-- see subsequent chapter -->

Configuring a barcode reader

Let’s write some JavaScript to attach a barcode reader to the HTML. The factor that can host the barcode reader has an ID worth of scanner, so it may be referenced by way of a CSS selector #scanner. Assuming our tickets have Code 128 barcodes (the most typical kind, aside from the EAN/UPC codes utilized in retail), we’ll configure the BarcodeReader as follows:

let theBarcodeReader = null;

operate initializeBarcodeReader() {
    let configuration = {
        selector: '#scanner',
        engine: {
            symbologies: ['code128']
    new BarcodeReader(configuration).initialize()
        .then(reader => {
            reader.detected = (detections) => {
            theBarcodeReader = reader;
            return reader.begin();

We retailer a reference the newly created BarcodeReader in a variable so we will entry it later.

Dealing with barcode detections

When a barcode is detected, we’ll invoke displayTicket() to show its the ticket quantity, together with some mock knowledge on the ticket holder. In a real-life app, this might be the place the place we’d situation an HTTP request utilizing the fetch API and lookup knowledge related to the ticket from a database.

Right here, we simply show the values, pause the scanning and allow the motion buttons. The motion buttons will clear the displayed values and resume the barcode scanning:

const admitButton = doc.getElementById('admit_button');
const denyButton = doc.getElementById('deny_button');
const ticketNumberLabel = doc.getElementById('ticket_number');
const ticketHolderLabel = doc.getElementById('ticket_holder');

operate displayTicket(ticketNumber) {


    ticketNumberLabel.innerText = ticketNumber;
    ticketHolderLabel.innerText = 'John Doe'; 
    admitButton.disabled = false;
    denyButton.disabled = false;

operate resumeScanning() {
    ticketNumberLabel.innerText = '-';
    ticketHolderLabel.innerText = '-';
    admitButton.disabled = true;
    denyButton.disabled = true;


admitButton.onclick = () => {
admitButton.disabled = true;
denyButton.onclick = () => {
denyButton.disabled = true;

Placing all of it collectively

To maintain issues so simple as attainable, I’ve chosen to place the whole app in a single HTML file, with the CSS kinds and JavaScript code inlined within the HTML. That is actually not a really useful apply, nevertheless it retains the instance lean and serves as a helpful reminder that internet app growth will be this straightforward!

The one HTML file in its entirety is out there on GitHub.

Right here’s a demo of the app doing its work:


On this article, I’ve proven tips on how to create a easy ticket scanning app that makes use of the STRICH Barcode Scanning SDK. Internet apps supply compelling benefits over native apps, particularly for in-house apps that don’t must be within the App Retailer. Trendy internet browsers, mixed with a succesful SDK like STRICH, make creating user-friendly barcode scanning apps quick, cost-efficient and enjoyable.

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