View as markdown
Copy for LLM Open in ChatGPT Open in Claude Open in Perplexity

Preload

Experimental

Commands

Preload.enable

Preload.disable

Events

Preload.ruleSetUpdated

Upsert. Currently, it is only emitted when a rule set added.

Parameters
Name Type Description
ruleSet RuleSet

Preload.ruleSetRemoved

Parameters
Name Type Description
id RuleSetId

Preload.preloadEnabledStateUpdated

Fired when a preload enabled state is updated.

Parameters
Name Type Description
disabledByPreference boolean
disabledByDataSaver boolean
disabledByBatterySaver boolean
disabledByHoldbackPrefetchSpeculationRules boolean
disabledByHoldbackPrerenderSpeculationRules boolean

Preload.prefetchStatusUpdated

Fired when a prefetch attempt is updated.

Parameters
Name Type Description
key PreloadingAttemptKey
pipelineId PreloadPipelineId
initiatingFrameId Page.FrameId The frame id of the frame initiating prefetch.
prefetchUrl string
status PreloadingStatus
prefetchStatus PrefetchStatus
requestId Network.RequestId

Preload.prerenderStatusUpdated

Fired when a prerender attempt is updated.

Parameters
Name Type Description
key PreloadingAttemptKey
pipelineId PreloadPipelineId
status PreloadingStatus
prerenderStatus (optional) PrerenderFinalStatus
disallowedMojoInterface (optional) string This is used to give users more information about the name of Mojo interface
that is incompatible with prerender and has caused the cancellation of the attempt.
mismatchedHeaders (optional) array<PrerenderMismatchedHeaders>

Preload.preloadingAttemptSourcesUpdated

Send a list of sources for all preloading attempts in a document.

Parameters
Name Type Description
loaderId Network.LoaderId
preloadingAttemptSources array<PreloadingAttemptSource>

Types

RuleSetId

(string)

Unique id

RuleSet

(object)

Corresponds to SpeculationRuleSet

Properties
Name Type Description
id RuleSetId
loaderId Network.LoaderId Identifies a document which the rule set is associated with.
sourceText string Source text of JSON representing the rule set. If it comes from
`<script>` tag, it is the textContent of the node. Note that it is
a JSON for valid case.

See also:
- https://wicg.github.io/nav-speculation/speculation-rules.html
- https://github.com/WICG/nav-speculation/blob/main/triggers.md
backendNodeId (optional) DOM.BackendNodeId A speculation rule set is either added through an inline
`<script>` tag or through an external resource via the
'Speculation-Rules' HTTP header. For the first case, we include
the BackendNodeId of the relevant `<script>` tag. For the second
case, we include the external URL where the rule set was loaded
from, and also RequestId if Network domain is enabled.

See also:
- https://wicg.github.io/nav-speculation/speculation-rules.html#speculation-rules-script
- https://wicg.github.io/nav-speculation/speculation-rules.html#speculation-rules-header
url (optional) string
requestId (optional) Network.RequestId
errorType (optional) RuleSetErrorType Error information
`errorMessage` is null iff `errorType` is null.
errorMessage (optional) Deprecated string TODO(https://crbug.com/1425354): Replace this property with structured error.
tag (optional) string For more details, see:
https://github.com/WICG/nav-speculation/blob/main/speculation-rules-tags.md

RuleSetErrorType

(string)
Allowed Values
  • SourceIsNotJsonObject
  • InvalidRulesSkipped
  • InvalidRulesetLevelTag

SpeculationAction

(string)

The type of preloading attempted. It corresponds to
mojom::SpeculationAction (although PrefetchWithSubresources is omitted as it
isn't being used by clients).

Allowed Values
  • Prefetch
  • Prerender
  • PrerenderUntilScript

SpeculationTargetHint

(string)

Corresponds to mojom::SpeculationTargetHint.
See https://github.com/WICG/nav-speculation/blob/main/triggers.md#window-name-targeting-hints

Allowed Values
  • Blank
  • Self

PreloadingAttemptKey

(object)

A key that identifies a preloading attempt.

The url used is the url specified by the trigger (i.e. the initial URL), and
not the final url that is navigated to. For example, prerendering allows
same-origin main frame navigations during the attempt, but the attempt is
still keyed with the initial URL.

Properties
Name Type Description
loaderId Network.LoaderId
action SpeculationAction
url string
targetHint (optional) SpeculationTargetHint

PreloadingAttemptSource

(object)

Lists sources for a preloading attempt, specifically the ids of rule sets
that had a speculation rule that triggered the attempt, and the
BackendNodeIds of <a href> or <area href> elements that triggered the
attempt (in the case of attempts triggered by a document rule). It is
possible for multiple rule sets and links to trigger a single attempt.

Properties
Name Type Description
key PreloadingAttemptKey
ruleSetIds array<RuleSetId>
nodeIds array<DOM.BackendNodeId>

PreloadPipelineId

(string)

Chrome manages different types of preloads together using a
concept of preloading pipeline. For example, if a site uses a
SpeculationRules for prerender, Chrome first starts a prefetch and
then upgrades it to prerender.

CDP events for them are emitted separately but they share
`PreloadPipelineId`.

PrerenderFinalStatus

(string)

List of FinalStatus reasons for Prerender2.

Allowed Values
  • Activated
  • Destroyed
  • LowEndDevice
  • InvalidSchemeRedirect
  • InvalidSchemeNavigation
  • NavigationRequestBlockedByCsp
  • MojoBinderPolicy
  • RendererProcessCrashed
  • RendererProcessKilled
  • Download
  • TriggerDestroyed
  • NavigationNotCommitted
  • NavigationBadHttpStatus
  • ClientCertRequested
  • NavigationRequestNetworkError
  • CancelAllHostsForTesting
  • DidFailLoad
  • Stop
  • SslCertificateError
  • LoginAuthRequested
  • UaChangeRequiresReload
  • BlockedByClient
  • AudioOutputDeviceRequested
  • MixedContent
  • TriggerBackgrounded
  • MemoryLimitExceeded
  • DataSaverEnabled
  • TriggerUrlHasEffectiveUrl
  • ActivatedBeforeStarted
  • InactivePageRestriction
  • StartFailed
  • TimeoutBackgrounded
  • CrossSiteRedirectInInitialNavigation
  • CrossSiteNavigationInInitialNavigation
  • SameSiteCrossOriginRedirectNotOptInInInitialNavigation
  • SameSiteCrossOriginNavigationNotOptInInInitialNavigation
  • ActivationNavigationParameterMismatch
  • ActivatedInBackground
  • EmbedderHostDisallowed
  • ActivationNavigationDestroyedBeforeSuccess
  • TabClosedByUserGesture
  • TabClosedWithoutUserGesture
  • PrimaryMainFrameRendererProcessCrashed
  • PrimaryMainFrameRendererProcessKilled
  • ActivationFramePolicyNotCompatible
  • PreloadingDisabled
  • BatterySaverEnabled
  • ActivatedDuringMainFrameNavigation
  • PreloadingUnsupportedByWebContents
  • CrossSiteRedirectInMainFrameNavigation
  • CrossSiteNavigationInMainFrameNavigation
  • SameSiteCrossOriginRedirectNotOptInInMainFrameNavigation
  • SameSiteCrossOriginNavigationNotOptInInMainFrameNavigation
  • MemoryPressureOnTrigger
  • MemoryPressureAfterTriggered
  • PrerenderingDisabledByDevTools
  • SpeculationRuleRemoved
  • ActivatedWithAuxiliaryBrowsingContexts
  • MaxNumOfRunningEagerPrerendersExceeded
  • MaxNumOfRunningNonEagerPrerendersExceeded
  • MaxNumOfRunningEmbedderPrerendersExceeded
  • PrerenderingUrlHasEffectiveUrl
  • RedirectedPrerenderingUrlHasEffectiveUrl
  • ActivationUrlHasEffectiveUrl
  • JavaScriptInterfaceAdded
  • JavaScriptInterfaceRemoved
  • AllPrerenderingCanceled
  • WindowClosed
  • SlowNetwork
  • OtherPrerenderedPageActivated
  • V8OptimizerDisabled
  • PrerenderFailedDuringPrefetch
  • BrowsingDataRemoved
  • PrerenderHostReused

PreloadingStatus

(string)

Preloading status values, see also PreloadingTriggeringOutcome. This
status is shared by prefetchStatusUpdated and prerenderStatusUpdated.

Allowed Values
  • Pending
  • Running
  • Ready
  • Success
  • Failure
  • NotSupported

PrefetchStatus

(string)

TODO(https://crbug.com/1384419): revisit the list of PrefetchStatus and
filter out the ones that aren't necessary to the developers.

Allowed Values
  • PrefetchAllowed
  • PrefetchFailedIneligibleRedirect
  • PrefetchFailedInvalidRedirect
  • PrefetchFailedMIMENotSupported
  • PrefetchFailedNetError
  • PrefetchFailedNon2XX
  • PrefetchEvictedAfterBrowsingDataRemoved
  • PrefetchEvictedAfterCandidateRemoved
  • PrefetchEvictedForNewerPrefetch
  • PrefetchHeldback
  • PrefetchIneligibleRetryAfter
  • PrefetchIsPrivacyDecoy
  • PrefetchIsStale
  • PrefetchNotEligibleBrowserContextOffTheRecord
  • PrefetchNotEligibleDataSaverEnabled
  • PrefetchNotEligibleExistingProxy
  • PrefetchNotEligibleHostIsNonUnique
  • PrefetchNotEligibleNonDefaultStoragePartition
  • PrefetchNotEligibleSameSiteCrossOriginPrefetchRequiredProxy
  • PrefetchNotEligibleSchemeIsNotHttps
  • PrefetchNotEligibleUserHasCookies
  • PrefetchNotEligibleUserHasServiceWorker
  • PrefetchNotEligibleUserHasServiceWorkerNoFetchHandler
  • PrefetchNotEligibleRedirectFromServiceWorker
  • PrefetchNotEligibleRedirectToServiceWorker
  • PrefetchNotEligibleBatterySaverEnabled
  • PrefetchNotEligiblePreloadingDisabled
  • PrefetchNotFinishedInTime
  • PrefetchNotStarted
  • PrefetchNotUsedCookiesChanged
  • PrefetchProxyNotAvailable
  • PrefetchResponseUsed
  • PrefetchSuccessfulButNotUsed
  • PrefetchNotUsedProbeFailed

PrerenderMismatchedHeaders

(object)

Information of headers to be displayed when the header mismatch occurred.

Properties
Name Type Description
headerName string
initialValue (optional) string
activationValue (optional) string

Summary