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 await are 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.
• BigInt support. Try out JavaScript's new arbitrary-precision integer in the Console.
• Adding property paths to the Watch pane. Add properties from the Scope pane to the Watch pane.
• "Show timestamps" moved to Settings.

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:

1. Open the Console.
2. Open Console Settings .
3. 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

Notes:

• 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 #

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. 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.