51Degrees Device Detection Node.js  4.1

51Degrees Device Detection for Node.js


This example shows how to use 51Degrees on-premise device detection to determine whether a given User-Agent corresponds to a mobile device or not.

This example is available in full on GitHub.

This example requires a local data file. Free data files can be acquired by pulling the submodules under this repository or from the device-detection-data GitHub repository.

Expected output:

Is user agent Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.97 Safari/537.36 a mobile? false

Is user agent Mozilla/5.0 (iPhone; CPU iPhone OS 11_2 like Mac OS X) AppleWebKit/604.4.7 (KHTML, like Gecko) Mobile/15C114 a mobile? true

/* *********************************************************************
* This Original Work is copyright of 51 Degrees Mobile Experts Limited.
* Copyright 2019 51 Degrees Mobile Experts Limited, 5 Charlotte Close,
* Caversham, Reading, Berkshire, United Kingdom RG4 7BY.
* This Original Work is licensed under the European Union Public Licence (EUPL)
* v.1.2 and is subject to its terms as set out below.
* If a copy of the EUPL was not distributed with this file, You can obtain
* one at https://opensource.org/licenses/EUPL-1.2.
* The 'Compatible Licences' set out in the Appendix to the EUPL (as may be
* amended by the European Commission) shall be deemed incompatible for
* the purposes of the Work and the provisions of the compatibility
* clause in Article 5 of the EUPL shall not apply.
* If using the Work as, or as part of, a network application, by
* including the attribution notice(s) required under Article 5 of the EUPL
* in the end user terms of the application under an appropriate heading,
* such notice(s) shall fulfill the requirements of that article.
* ********************************************************************* */
const FiftyOneDegreesDeviceDetection = require((process.env.directory || __dirname) + '/../../');
// Load in a datafile
const datafile = (process.env.directory || __dirname) + '/../../device-detection-cxx/device-detection-data/51Degrees-LiteV4.1.hash';
// Check if datafiele exists
const fs = require('fs');
if (!fs.existsSync(datafile)) {
console.error("The datafile required by this example is not present. Please ensure that the 'device-detection-data' submodule has been fetched.");
throw ("No data file at '" + datafile + "'");
// Create the device detection pipeline with the desired settings.
const pipeline = new FiftyOneDegreesDeviceDetection.DeviceDetectionPipelineBuilder({
performanceProfile: 'MaxPerformance',
dataFile: datafile,
autoUpdate: false
// To monitor the pipeline we can put in listeners for various log events.
// Valid types are info, debug, warn, error
pipeline.on('error', console.error);
// Here we make a function that gets a userAgent as evidence and
// uses the Device Detection Engine to detect if it is a mobile or not
const checkIfMobile = async function (userAgent) {
// Create a FlowData element
// This is used to add evidence and process it through the
// FlowElements in the Pipeline.
const flowData = pipeline.createFlowData();
// Add the User-Agent as evidence
flowData.evidence.add('header.user-agent', userAgent);
// Run process on the flowData (this returns a promise)
await flowData.process();
// Check the ismobile property
// this returns an AspectPropertyValue wrapper
// letting you check if a value is set and if not why not
const ismobile = flowData.device.ismobile;
if (ismobile.hasValue) {
console.log(`Is user agent ${userAgent} a mobile? ${ismobile.value}`);
} else {
// Echo out why the value isn't meaningful
const desktopUA = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.97 Safari/537.36';
const iPhoneUA = 'Mozilla/5.0 (iPhone; CPU iPhone OS 11_2 like Mac OS X) AppleWebKit/604.4.7 (KHTML, like Gecko) Mobile/15C114';