What's New In DevTools (Chrome 68)
New to DevTools in Chrome 68:
- Eager Evaluation. As you type expressions, the Console previews the result.
- Argument hints. As you type functions, the Console shows you the expected arguments for that function.
- Function autocompletion. After typing a function call such as
document.querySelector('p'), the Console shows you the functions and properties that the return value supports.
- ES2017 keywords in the Console. Keywords such as
awaitare now available in the Console's autocomplete UI.
- Lighthouse 3.0 in the Audits panel. Faster, more consistent audits, a new UI, and new audits.
- Adding property paths to the Watch pane. Add properties from the Scope pane to the Watch pane.
- "Show timestamps" moved to Settings.
Note: Check what version of Chrome you're running at
chrome://version. If you're running an earlier version, these features won't exist. If you're running a later version, these features may have changed. Chrome auto-updates to a new major version about every 6 weeks.
Read on, or watch the video version of the release notes, below.
Assistive Console #
Chrome 68 ships with a few new Console features related to autocompletion and previewing.
Eager Evaluation #
When you type an expression in the Console, the Console can now show a preview of the result of that expression below your cursor.
Figure 1. The Console is printing the result of the
sort() operation before it has been explicitly executed
To enable Eager Evaluation:
- Open the Console.
- Open Console Settings .
- Enable the Eager evaluation checkbox.
DevTools does not eager evaluate if the expression causes side effects.
Argument hints #
As you're typing out functions, the Console now shows you the arguments that the function expects.
Figure 2. Various examples of argument hints in the Console
- A question mark before an arg, such as
?options, represents an optional arg.
- An ellipsis before an arg, such as
...items, represents a spread.
- Some functions, such as
CSS.supports(), accept multiple argument signatures.
Autocomplete after function executions #
Note: This feature depends on Eager Evaluation, which needs to be enabled from Console Settings .
After enabling Eager Evaluation, the Console now also shows you which properties and functions are available after you type out a function.
Figure 3. The top screenshot represents the old behavior, and the bottom screenshot represents the new behavior that supports function autocompletion
ES2017 keywords in autocomplete #
ES2017 keywords, such as
await, are now available in the Console's autocomplete UI.
Figure 4. The Console now suggests
await in its autocomplete UI
Faster, more reliable audits, a new UI, and new audits #
Chrome 68 ships with Lighthouse 3.0. The next sections are a roundup of some of the biggest changes. See Announcing Lighthouse 3.0 for the full story.
Faster, more reliable audits #
Lighthouse 3.0 has a new internal auditing engine, codenamed Lantern, which completes your audits faster, and with less variance between runs.
New UI #
Lighthouse 3.0 also brings a new UI, thanks to a collaboration between the Lighthouse and Chrome UX (Research & Design) teams.
Figure 5. The new report UI in Lighthouse 3.0
New audits #
Lighthouse 3.0 also ships with 4 new audits:
- First Contentful Paint
- robots.txt is not valid
- Use video formats for animated content
- Avoid multiple, costly round trips to any origin
BigInt support #
Chrome 68 supports a new numeric primitive called
BigInt lets you represent integers with arbitrary precision. Try it out in the Console:
Figure 6. An example of
BigInt in the Console
Add property path to watch #
While paused on a breakpoint, right-click a property in the Scope pane and select Add property path to watch to add that property to the Watch pane.
Figure 7. An example of Add property path to watch
"Show timestamps" moved to settings #
The Show timestamps checkbox previously in Console Settings has moved to Settings.