Sizes, emulation and location
Test the page at other screen sizes, emulate devices, network and CPU, and override geolocation.
Three adjustments that change the environment in which the page sees itself: the screen size, the network and processing conditions, and the reported geographic position.
Viewport sizes
- In the toolbar there is a device group that applies a size preset.
- In the three-dot menu there is the size list, with presets covering from small phone to large laptop, including tablet.
- The chosen preset is remembered per tab — each tab has its own.
A hand-set size is also possible, with width, height, scale and mobile mode.
A viewport override hides the real layout until it is removed. If the page looks odd after a test, confirm whether a size is still applied to that tab.
Device, network and CPU emulation
From the command line you can apply emulations that go beyond size:
| Emulation | What it does |
|---|---|
| Device | Applies a known device to the tab |
| CPU | Applies processing throttling, with an integer rate greater than or equal to 1 |
| Network | Applies a network condition: slow-3g, fast-3g, slow-4g, fast-4g, offline or no-throttling |
| Offline | Turns offline mode on and off |
| Media preferences | Sets color scheme and reduced-motion preference |
The network emulation result prints the effective rates applied — that is what lets you state what was emulated instead of assuming it.
Reset clears CPU and network at once. If you emulated a network to measure something, reset before the next measurement: forgotten throttling contaminates the next number.
Geolocation
Geolocation overrides the position reported to the page. You must provide latitude and longitude; accuracy is optional.
A fake position changes what the page shows and what it may consent to. Regional content, notices and consents can react to the position — including in ways you do not want recorded on a real account.
Limits
- The emulation applies per tab and lasts while it is applied.
- The viewport override and the emulation do not change the app window: they change what the page thinks the screen is.
- The effective rates and conditions must be read from the command’s output — there is no promise that the machine can reproduce exactly the requested condition.