How to print raw PRN commands/files from Javascript
Product JSPrintManager Published 09/22/2020 Updated 09/22/2020 Author Neodynamic
Overview
A PRN file contains raw commands instructions for a printer which are usually created by a printer driver. It is not a simple text file you can open with a text editor software and print it as is, because it contains commands instructions in the form of bytes that must be sent to the printer without any modifications so the printer firmware can process them.
In this walkthrough, you'll learn how to print raw PRN commands from Javascript directly to the client printer without displaying a print dialog at all. You'll be able to print PRN commands to the Default client printer as well as to any other installed printer at the client machine. This solution works with any popular browser like Chrome, Firefox, Edge & Safari on Windows, Linux, Raspberry Pi or Mac systems!
Follow up these steps
- Be sure you install in your dev machine JSPrintManager (JSPM) (Available for Windows, Linux, Raspberry Pi & Mac)
This small app must be installed on each client that will print from your website! - By using your favorite Web Development IDE or Text Editor, create a new HTML file like index.html
Copy/paste the following snipped codes:HTML Code
<div style="text-align:center"> <h1>Print PRN commands/files from Javascript</h1> <hr /> <label class="checkbox"> <input type="checkbox" id="useDefaultPrinter" /> <strong>Print to Default printer</strong> </label> <p>or...</p> <div id="installedPrinters"> <label for="installedPrinterName">Select an installed Printer:</label> <select name="installedPrinterName" id="installedPrinterName"></select> </div> <br /><br /> <button type="button" onclick="print();">Print Now...</button> </div>Script References
- Download JSPrintManager.js
- Copy all of these *.js files to the same folder where your html page is located and the add the following script references to your page.
<script src="JSPrintManager.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/bluebird/3.3.5/bluebird.min.js"></script> <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>Script Code
<script> //WebSocket settings JSPM.JSPrintManager.auto_reconnect = true; JSPM.JSPrintManager.start(); JSPM.JSPrintManager.WS.onStatusChanged = function () { if (jspmWSStatus()) { //get client installed printers JSPM.JSPrintManager.getPrinters().then(function (myPrinters) { var options = ''; for (var i = 0; i < myPrinters.length; i++) { options += '<option>' + myPrinters[i] + '</option>'; } $('#installedPrinterName').html(options); }); } }; //Check JSPM WebSocket status function jspmWSStatus() { if (JSPM.JSPrintManager.websocket_status == JSPM.WSStatus.Open) return true; else if (JSPM.JSPrintManager.websocket_status == JSPM.WSStatus.Closed) { alert('JSPrintManager (JSPM) is not installed or not running! Download JSPM Client App from https://neodynamic.com/downloads/jspm'); return false; } else if (JSPM.JSPrintManager.websocket_status == JSPM.WSStatus.Blocked) { alert('JSPM has blocked this website!'); return false; } } //Do printing... function print(o) { if (jspmWSStatus()) { var xhr = new XMLHttpRequest(); // ###### IMPORTANT ################################################ // CHANGE the URL/path of the PRN file in the following line of code // ################################################################# xhr.open('GET', '/the-printer-commands.prn', true); xhr.responseType = 'arraybuffer'; xhr.onload = function (e) { if (this.status == 200) { //console.log(xhr.response); //Create a ClientPrintJob var cpj = new JSPM.ClientPrintJob(); //Set Printer type (Refer to the help, there many of them!) if ($('#useDefaultPrinter').prop('checked')) { cpj.clientPrinter = new JSPM.DefaultPrinter(); } else { cpj.clientPrinter = new JSPM.InstalledPrinter($('#installedPrinterName').val()); } //Set printer commands... cpj.binaryPrinterCommands = new Uint8Array(xhr.response); //Send print job to printer! cpj.sendToClient(); } } xhr.send(); } } </script> - That's it! Run your website and test it. Click on Print Now... to print the PRN Commands without print dialog. You can print it to the Default client printer or you can get a list of the installed printers available at the client machine.
NOTE You can also print directly to any LPT Parallel Port, RS232 Serial Port or IP/Ethernet Printer although these scenarios have not been considered in this article for simplicity. For further details on those scenarios, please contact our tech support.