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How to emulate mobile devices with Playwright
Playwright controls headless desktop browsers that can also emulate mobile devices. And while device emulation can’t replace testing on mobile devices entirely, it’s a practical and quick-to-setup approach to testing mobile scenarios.
Device emulation is well suited to test if your site behaves correctly across multiple viewport sizes and correctly handles user-agent strings. But if your site relies on device-specific browser features, an iPhone emulation running in a Chromium browser might lead to false positives.
This guide explains how to define viewport sizes, device pixel ratio and user-agent strings using Playwright.
Defining the user agent string
If your site parses the user agent string to serve a different experience to mobile users, define the userAgent in your automation scripts.
const { chromium } = require("playwright")
;(async () => {
const browser = await chromium.launch()
const page = await browser.newPage({
// define the iPhone SE user agent
userAgent:
"Mozilla/5.0 (iPhone; CPU iPhone OS 10_3_1 like Mac OS X) AppleWebKit/603.1.30 (KHTML, like Gecko) Version/16.0 Mobile/14E304 Safari/602.1",
})
await page.goto("https://danube-web.shop/")
// perform your tests
await browser.close()
})()
Defining viewport size and pixel density
If your site follows responsive web design practices and renders elements depending on device viewport size, define a mobile viewport and pixel density.
const { chromium } = require("playwright")
;(async () => {
const browser = await chromium.launch()
const page = await browser.newPage({
// define the iPhone SE viewport size and pixel density
viewport: {
width: 320,
height: 568,
},
deviceScaleFactor: 2,
})
await page.goto("https://danube-web.shop/")
// perform your tests
await browser.close()
})()
Use built-in device registries
Playwright includes a built-in device registry to access mobile device characteristics quickly.
Leverage the pre-defined devices to emulate mobile devices.
const { chromium, devices } = require("playwright")
const iPhone = devices['iPhone SE'];
;(async () => {
const browser = await chromium.launch()
const page = await browser.newPage({
// emulate the iPhone SE
...iPhone
})
await page.goto("https://danube-web.shop/")
// perform your tests
await browser.close()
})()