Chrome DevTools

HeadlessExperimental Domain

This domain provides experimental commands only supported in headless mode.

Experimental

Methods

Types

Methods

Chrome DevTools

HeadlessExperimental.beginFrame #

Sends a BeginFrame to the target and returns when the frame was completed. Optionally captures a screenshot from the resulting frame. Requires that the target was created with enabled BeginFrameControl. Designed for use with --run-all-compositor-stages-before-draw, see also https://goo.gle/chrome-headless-rendering for more background.

Parameters

frameTimeTicks
Optional
number

Timestamp of this BeginFrame in Renderer TimeTicks (milliseconds of uptime). If not set, the current time will be used.

interval
Optional
number

The interval between BeginFrames that is reported to the compositor, in milliseconds. Defaults to a 60 frames/second interval, i.e. about 16.666 milliseconds.

noDisplayUpdates
Optional
boolean

Whether updates should not be committed and drawn onto the display. False by default. If true, only side effects of the BeginFrame will be run, such as layout and animations, but any visual updates may not be visible on the display or in screenshots.

screenshot
Optional
ScreenshotParams

If set, a screenshot of the frame will be captured and returned in the response. Otherwise, no screenshot will be captured. Note that capturing a screenshot can fail, for example, during renderer initialization. In such a case, no screenshot data will be returned.

Return object

hasDamage
boolean

Whether the BeginFrame resulted in damage and, thus, a new frame was committed to the display. Reported for diagnostic uses, may be removed in the future.

screenshotData
Optional
string

Base64-encoded image data of the screenshot, if one was requested and successfully taken. (Encoded as a base64 string when passed over JSON)

Chrome DevTools

HeadlessExperimental.disable Deprecated#

Disables headless events for the target.

Chrome DevTools

HeadlessExperimental.enable Deprecated#

Enables headless events for the target.

Types

Chrome DevTools

HeadlessExperimental.ScreenshotParams #

Encoding options for a screenshot.

Type: object

Properties

format
Optional
string

Image compression format (defaults to png).

Allowed values: jpeg, png, webp

quality
Optional
integer

Compression quality from range [0..100] (jpeg and webp only).

optimizeForSpeed
Optional
boolean

Optimize image encoding for speed, not for resulting size (defaults to false)