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Import KnownDevices from puppeteer, select a profile by its exact documented key, and call page.emulate(profile) before navigating. For example, use KnownDevices['iPhone 17 Pro'] to apply that profile’s user agent and viewport to a Puppeteer page.
Use a named device profile before navigation
This example follows Puppeteer’s documented sequence. Replace the target URL with the page you want to check.
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import puppeteer, {KnownDevices} from 'puppeteer';
const device = KnownDevices['iPhone 17 Pro'];
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.emulate(device);
await page.goto('https://example.com');
// Run checks here.
await browser.close();- Import
KnownDevicesfrom the Puppeteer package used by your project. - Choose a profile using its exact string key, such as
KnownDevices['iPhone 17 Pro']. - Launch the browser and create a page.
- Call and await
page.emulate(device). - Navigate with
page.goto(), then run your checks.
Call emulation before navigation. Puppeteer says the method resizes the page and recommends setting the profile first because many sites do not expect phones to change size. See the Page.emulate() reference.
What KnownDevices and page.emulate() configure
KnownDevices is a readonly record of named device profiles. The Device interface has userAgent and viewport properties. Puppeteer describes page.emulate(device) as a shortcut for calling Page.setUserAgent() and Page.setViewport(); it applies the profile’s user agent and metrics to the page.
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This is browser-side profile emulation, not a promise that a desktop browser becomes identical to a physical phone or tablet. The API references document the user agent and viewport, but do not claim complete hardware or operating-system simulation. If a result depends on real hardware, OS behavior, or a browser behavior the profile does not represent, verify it separately on that environment.
Choose and verify the profile key
The API reference includes portrait and landscape profile names. Examples include iPhone 17 Pro, iPhone 17 Pro landscape, iPad, iPad landscape, Galaxy S9+, and Pixel 5. These are examples, not a guarantee that every key is present in every installed release.
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- Use the exact spelling and punctuation of a key; portrait and landscape variants are separate entries where listed.
- Check the KnownDevices API reference and the type definitions in your installed Puppeteer package for the keys available to your version.
- When comparing profiles, inspect the particular key and its viewport and user-agent values that matter to the page under test.
The official KnownDevices reference displayed version 25.11.0 when accessed October 3, 2026. The Page.emulate() reference displayed version 25.12.0 on that date; these are documentation version labels, not publication dates. The Device interface reference displayed version 25.11.0. Check the current references and your installed package rather than assuming the displayed list or version is unchanged.
Troubleshoot common issues
The selected profile is undefined
A misspelled key, a key absent from your installed Puppeteer release, or a portrait/landscape name mismatch can leave the selection without a usable profile. Compare the string with the API reference and your installed package’s types, then use an exact available key.
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The page appears at the wrong size
Confirm that you awaited page.emulate(device) and called it before page.goto(). Also check that you selected the intended orientation: a landscape profile has different viewport dimensions from its portrait counterpart.
The site still behaves differently from a real device
The documented profile configures user-agent and viewport behavior; it does not establish that every physical-device, operating-system, or hardware behavior is reproduced. Reproduce device-dependent issues in the relevant real environment.
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Or skip the browser setup
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Frequently Asked Questions
Does Puppeteer’s device emulation test a site on a physical iPhone or tablet?
No. It applies the profile’s documented user-agent and viewport settings; it does not guarantee physical hardware or operating-system simulation.
Do I need to set the profile again for each new page?
The example applies the profile to the specific Page object. Apply emulation to each page you intend to use with that profile.
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