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What's New In DevTools (Chrome 88)

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Faster DevTools startup

DevTools startup now is ~37% faster in terms of JavaScript compilation (from 6.9s down to 5s)! ?

The team did some optimization to reduce the performance overhead of serialisation, parsing and deserialisation during the startup.

There will be an upcoming engineering blog post explaining the implementation in detail. Stay tuned!

Chromium issue: 1029427

New CSS angle visualization tools

DevTools now has better support for CSS angle debugging!

When an HTML element on your page has CSS angle applied to it (e.g. background: linear-gradient(angle, color-stop1, color-stop2), transform: rotate(angle)), a clock icon is shown next to the angle in the Styles pane. Click on the clock icon to toggle the clock overlay. Click anywhere in the clock or drag the needle to change the angle!

There are mouse and keyboard shortcuts to change the angle value as well, check out our documentation to learn more!

Chromium issues: 1126178, 1138633

Emulate unsupported image types

DevTools added two new emulations in the Rendering tab, allowing you to disable AVIF and WebP image formats. These new emulations make it easier for developers to test different image loading scenarios without having to switch browsers.

Suppose we have the following HTML code to serve an image in AVIF and WebP for newer browsers, with a fallback PNG image for older browsers.

<picture>
  <source srcset="test.avif" type="image/avif">
  <source srcset="test.webp" type="image/webp">
  <img src="test.png" alt="A test image">
</picture>

Open the Rendering tab, select “Disable AVIF image format” and refresh the page. Hover over the img src. The current image src (currentSrc) is now the fallback WebP image.

Chromium issue: 1130556

Simulate storage quota size in the Storage pane

You can now override storage quota size in the Storage pane. This feature gives you the ability to simulate different devices and test the behavior of your apps in low disk availability scenarios.

Go to Application > Storage, enable the Simulate custom storage quota checkbox, and enter any valid number to simulate the storage quota.

Chromium issues: 945786, 1146985

New Web Vitals lane in the Performance panel recordings

Performance recordings now have an option to display Web Vitals information.

After recording your load performance, enable the Web Vitals checkbox in the Performance panel to view the new Web Vitals lane.

The lane currently displays Web Vitals information such as First Contentful Paint (FCP), Largest Contentful Paint (LCP) and Layout Shift (LS).

Check out web.dev/vitals to learn more about how to optimize user experience with the Web Vitals metrics.

Chromium issue: N/A

Report CORS errors in the Network panel

DevTools now shows CORS error when a network request is failed due to Cross-origin Resource Sharing (CORS).

In the Network panel, observe the failed CORS network request. The status column shows “CORS error”. Hover over on the error, the tooltip now shows the error code. Previously, DevTools only showed generic “(failed)” status for CORS errors.

This lays the foundation for our next enhancements on providing more detailed description of the CORS problems!

Chromium issue: 1141824

Frame details view updates

Cross-origin isolation information in the Frame details view

The cross-origin isolated status is now displayed under the Security & Isolation section.

The new API availability section displays the availability of SharedArrayBuffers (SAB) and whether they can be shared using postMessage().

A deprecation warning will show if the SAB and postMessage() is currently available, but the context is not cross-origin isolated. Learn more about cross-origin isolation and why it will be required for features like SharedArrayBuffers in this article.

Chromium issue: 1139899

New Web Workers information in the Frame details view

DevTools now displays dedicated web workers under the frame which creates them.

In the Application panel, expand a frame with web workers, then select a worker under the Workers tree to view the web worker's details.

Chromium issues: 1122507, 1051466

Display opener frame details for opened windows

You can now view the details about which frame caused the opening of another Window.

Select an opened window under the Frames tree to view the window details. Click on the Opener Frame link to reveal the opener in the Elements panel.

Chromium issue: 1107766

Open Network panel from the Service Workers pane

View all service worker (SW) request routing information with the new Network requests link. This provides developers added context when debugging the SW.

Go to Application > Service Workers, click on the Network requests of a SW. The Network panel is opened in the bottom panel displaying all service worker related requests (the network requests are filtered by “is:service-worker-intercepted”).

Chromium issue: N/A

New copy options in the Network panel

Copy property value

The new “Copy value” option in the context menu lets you copy the property value of a network request.

In the Network panel, click on a network request to open the Headers pane. Right click on one of the properties under these section: Request payload (JSON) Form Data Query String Parameters Request Headers Response Headers

Then, you can select Copy value to copy the property value to your clipboard.

Chromium issue: 1132084

Copy stacktrace for network initiator

Right-click a network request, then select Copy stacktrace to copy the stacktrace to your clipboard.

Chromium issue: 1139615

Wasm debugging updates

Preview Wasm variable value on mouseover

When hovering over a variable in WebAssembly (Wasm) disassembly while paused on a breakpoint, DevTools now shows the variable current value.

In the Sources panel, open a Wasm file, put a breakpoint and refresh the page. Hover to a variable to see the value.

Chromium issues: 1058836, 1071432

Evaluate Wasm variable in the Console

You can now evaluate Wasm variable in the Console while paused on a breakpoint.

In this example, we put a breakpoint on the line local.get $input. When debugging, type $input in the Console will return the current value of the variable, which is 4 in this case.

Chromium issue: 1127914

Consistent units of measurement for file/memory sizes

DevTools now consistently use kB for displaying file/memory sizes. Previously DevTools mixed kB (1000 bytes) and KiB (1024 bytes). For example, the Network panel previously used “kB” labels but actually performed calculations using KiB, which caused needless confusion.

Chromium issue: 1035309

Highlight pseudo elements in the Elements panel

DevTools has increased the color contrast of pseudo elements to help you better spot them.

Chromium issue: 1143833

Experimental features

CSS Flexbox debugging tools

Flexbox debugging tools are coming!

For starters, DevTools now shows a flex badge in the Elements panel for elements with display: flex applied to it.

Beside that, new alignment icons are added in the following flexbox properties:

• flex-direction
• align-items
• align-content
• align-self
• justify-items
• justify-content

On top of that, these icons are context-aware. The icon direction will be adjusted according to:

• flex-direction
• direction
• writing-mode

These icons aim to help you better visualize the flexbox layout of the page.

Here is the design doc of the Flexbox tooling features. More features will be added soon.

Give it a try and let us know what you think!

Chromium issues: 1144090, 1139945

Customize chords keyboard shortcuts

DevTools added experimental support for customize keyboard shortcuts since last release.

You can now create chords (a.k.a multi-keypress shortcuts) in the shortcut editor.

Go to Settings > Shortcuts, hovering on a command and click the Edit button (pen icon) to customize the chords shortcut.

Chromium issue: 174309

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This content originally appeared on Updates and was authored by