Preload

This CDP domain is experimental.

• Types

• Commands

• Events

Types

Generally, you do not need to instantiate CDP types yourself. Instead, the API creates objects for you as return values from commands, and then you can use those objects as arguments to other commands.

class RuleSetId

Unique id

class RuleSet(id_, loader_id, source_text, backend_node_id=None, url=None, request_id=None, error_type=None, error_message=None)

Corresponds to SpeculationRuleSet

id_: RuleSetId

loader_id: LoaderId

Identifies a document which the rule set is associated with.

source_text: str

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

backend_node_id: Optional[BackendNodeId] = None

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[str] = None

request_id: Optional[RequestId] = None

error_type: Optional[RuleSetErrorType] = None

Error information errorMessage is null iff errorType is null.

error_message: Optional[str] = None

Replace this property with structured error.

Type:

TODO(https

Type:

//crbug.com/1425354)

class RuleSetErrorType(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

SOURCE_IS_NOT_JSON_OBJECT = 'SourceIsNotJsonObject'

INVALID_RULES_SKIPPED = 'InvalidRulesSkipped'

INVALID_RULESET_LEVEL_TAG = 'InvalidRulesetLevelTag'

class SpeculationAction(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

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

PREFETCH = 'Prefetch'

PRERENDER = 'Prerender'

class SpeculationTargetHint(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

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

BLANK = 'Blank'

SELF = 'Self'

class PreloadingAttemptKey(loader_id, action, url, target_hint=None)

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.

loader_id: LoaderId

action: SpeculationAction

url: str

target_hint: Optional[SpeculationTargetHint] = None

class PreloadingAttemptSource(key, rule_set_ids, node_ids)

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.

key: PreloadingAttemptKey

rule_set_ids: List[RuleSetId]

node_ids: List[BackendNodeId]

class PreloadPipelineId

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.

class PrerenderFinalStatus(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

List of FinalStatus reasons for Prerender2.

ACTIVATED = 'Activated'

DESTROYED = 'Destroyed'

LOW_END_DEVICE = 'LowEndDevice'

INVALID_SCHEME_REDIRECT = 'InvalidSchemeRedirect'

INVALID_SCHEME_NAVIGATION = 'InvalidSchemeNavigation'

NAVIGATION_REQUEST_BLOCKED_BY_CSP = 'NavigationRequestBlockedByCsp'

MOJO_BINDER_POLICY = 'MojoBinderPolicy'

RENDERER_PROCESS_CRASHED = 'RendererProcessCrashed'

RENDERER_PROCESS_KILLED = 'RendererProcessKilled'

DOWNLOAD = 'Download'

TRIGGER_DESTROYED = 'TriggerDestroyed'

NAVIGATION_NOT_COMMITTED = 'NavigationNotCommitted'

NAVIGATION_BAD_HTTP_STATUS = 'NavigationBadHttpStatus'

CLIENT_CERT_REQUESTED = 'ClientCertRequested'

NAVIGATION_REQUEST_NETWORK_ERROR = 'NavigationRequestNetworkError'

CANCEL_ALL_HOSTS_FOR_TESTING = 'CancelAllHostsForTesting'

DID_FAIL_LOAD = 'DidFailLoad'

STOP = 'Stop'

SSL_CERTIFICATE_ERROR = 'SslCertificateError'

LOGIN_AUTH_REQUESTED = 'LoginAuthRequested'

UA_CHANGE_REQUIRES_RELOAD = 'UaChangeRequiresReload'

BLOCKED_BY_CLIENT = 'BlockedByClient'

AUDIO_OUTPUT_DEVICE_REQUESTED = 'AudioOutputDeviceRequested'

MIXED_CONTENT = 'MixedContent'

TRIGGER_BACKGROUNDED = 'TriggerBackgrounded'

MEMORY_LIMIT_EXCEEDED = 'MemoryLimitExceeded'

DATA_SAVER_ENABLED = 'DataSaverEnabled'

TRIGGER_URL_HAS_EFFECTIVE_URL = 'TriggerUrlHasEffectiveUrl'

ACTIVATED_BEFORE_STARTED = 'ActivatedBeforeStarted'

INACTIVE_PAGE_RESTRICTION = 'InactivePageRestriction'

START_FAILED = 'StartFailed'

TIMEOUT_BACKGROUNDED = 'TimeoutBackgrounded'

CROSS_SITE_REDIRECT_IN_INITIAL_NAVIGATION = 'CrossSiteRedirectInInitialNavigation'

CROSS_SITE_NAVIGATION_IN_INITIAL_NAVIGATION = 'CrossSiteNavigationInInitialNavigation'

SAME_SITE_CROSS_ORIGIN_REDIRECT_NOT_OPT_IN_IN_INITIAL_NAVIGATION = 'SameSiteCrossOriginRedirectNotOptInInInitialNavigation'

SAME_SITE_CROSS_ORIGIN_NAVIGATION_NOT_OPT_IN_IN_INITIAL_NAVIGATION = 'SameSiteCrossOriginNavigationNotOptInInInitialNavigation'

ACTIVATION_NAVIGATION_PARAMETER_MISMATCH = 'ActivationNavigationParameterMismatch'

ACTIVATED_IN_BACKGROUND = 'ActivatedInBackground'

EMBEDDER_HOST_DISALLOWED = 'EmbedderHostDisallowed'

ACTIVATION_NAVIGATION_DESTROYED_BEFORE_SUCCESS = 'ActivationNavigationDestroyedBeforeSuccess'

TAB_CLOSED_BY_USER_GESTURE = 'TabClosedByUserGesture'

TAB_CLOSED_WITHOUT_USER_GESTURE = 'TabClosedWithoutUserGesture'

PRIMARY_MAIN_FRAME_RENDERER_PROCESS_CRASHED = 'PrimaryMainFrameRendererProcessCrashed'

PRIMARY_MAIN_FRAME_RENDERER_PROCESS_KILLED = 'PrimaryMainFrameRendererProcessKilled'

ACTIVATION_FRAME_POLICY_NOT_COMPATIBLE = 'ActivationFramePolicyNotCompatible'

PRELOADING_DISABLED = 'PreloadingDisabled'

BATTERY_SAVER_ENABLED = 'BatterySaverEnabled'

ACTIVATED_DURING_MAIN_FRAME_NAVIGATION = 'ActivatedDuringMainFrameNavigation'

PRELOADING_UNSUPPORTED_BY_WEB_CONTENTS = 'PreloadingUnsupportedByWebContents'

CROSS_SITE_REDIRECT_IN_MAIN_FRAME_NAVIGATION = 'CrossSiteRedirectInMainFrameNavigation'

CROSS_SITE_NAVIGATION_IN_MAIN_FRAME_NAVIGATION = 'CrossSiteNavigationInMainFrameNavigation'

SAME_SITE_CROSS_ORIGIN_REDIRECT_NOT_OPT_IN_IN_MAIN_FRAME_NAVIGATION = 'SameSiteCrossOriginRedirectNotOptInInMainFrameNavigation'

SAME_SITE_CROSS_ORIGIN_NAVIGATION_NOT_OPT_IN_IN_MAIN_FRAME_NAVIGATION = 'SameSiteCrossOriginNavigationNotOptInInMainFrameNavigation'

MEMORY_PRESSURE_ON_TRIGGER = 'MemoryPressureOnTrigger'

MEMORY_PRESSURE_AFTER_TRIGGERED = 'MemoryPressureAfterTriggered'

PRERENDERING_DISABLED_BY_DEV_TOOLS = 'PrerenderingDisabledByDevTools'

SPECULATION_RULE_REMOVED = 'SpeculationRuleRemoved'

ACTIVATED_WITH_AUXILIARY_BROWSING_CONTEXTS = 'ActivatedWithAuxiliaryBrowsingContexts'

MAX_NUM_OF_RUNNING_EAGER_PRERENDERS_EXCEEDED = 'MaxNumOfRunningEagerPrerendersExceeded'

MAX_NUM_OF_RUNNING_NON_EAGER_PRERENDERS_EXCEEDED = 'MaxNumOfRunningNonEagerPrerendersExceeded'

MAX_NUM_OF_RUNNING_EMBEDDER_PRERENDERS_EXCEEDED = 'MaxNumOfRunningEmbedderPrerendersExceeded'

PRERENDERING_URL_HAS_EFFECTIVE_URL = 'PrerenderingUrlHasEffectiveUrl'

REDIRECTED_PRERENDERING_URL_HAS_EFFECTIVE_URL = 'RedirectedPrerenderingUrlHasEffectiveUrl'

ACTIVATION_URL_HAS_EFFECTIVE_URL = 'ActivationUrlHasEffectiveUrl'

JAVA_SCRIPT_INTERFACE_ADDED = 'JavaScriptInterfaceAdded'

JAVA_SCRIPT_INTERFACE_REMOVED = 'JavaScriptInterfaceRemoved'

ALL_PRERENDERING_CANCELED = 'AllPrerenderingCanceled'

WINDOW_CLOSED = 'WindowClosed'

SLOW_NETWORK = 'SlowNetwork'

OTHER_PRERENDERED_PAGE_ACTIVATED = 'OtherPrerenderedPageActivated'

V8_OPTIMIZER_DISABLED = 'V8OptimizerDisabled'

PRERENDER_FAILED_DURING_PREFETCH = 'PrerenderFailedDuringPrefetch'

BROWSING_DATA_REMOVED = 'BrowsingDataRemoved'

PRERENDER_HOST_REUSED = 'PrerenderHostReused'

class PreloadingStatus(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

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

PENDING = 'Pending'

RUNNING = 'Running'

READY = 'Ready'

SUCCESS = 'Success'

FAILURE = 'Failure'

NOT_SUPPORTED = 'NotSupported'

class PrefetchStatus(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

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

PREFETCH_ALLOWED = 'PrefetchAllowed'

PREFETCH_FAILED_INELIGIBLE_REDIRECT = 'PrefetchFailedIneligibleRedirect'

PREFETCH_FAILED_INVALID_REDIRECT = 'PrefetchFailedInvalidRedirect'

PREFETCH_FAILED_MIME_NOT_SUPPORTED = 'PrefetchFailedMIMENotSupported'

PREFETCH_FAILED_NET_ERROR = 'PrefetchFailedNetError'

PREFETCH_FAILED_NON2_XX = 'PrefetchFailedNon2XX'

PREFETCH_EVICTED_AFTER_BROWSING_DATA_REMOVED = 'PrefetchEvictedAfterBrowsingDataRemoved'

PREFETCH_EVICTED_AFTER_CANDIDATE_REMOVED = 'PrefetchEvictedAfterCandidateRemoved'

PREFETCH_EVICTED_FOR_NEWER_PREFETCH = 'PrefetchEvictedForNewerPrefetch'

PREFETCH_HELDBACK = 'PrefetchHeldback'

PREFETCH_INELIGIBLE_RETRY_AFTER = 'PrefetchIneligibleRetryAfter'

PREFETCH_IS_PRIVACY_DECOY = 'PrefetchIsPrivacyDecoy'

PREFETCH_IS_STALE = 'PrefetchIsStale'

PREFETCH_NOT_ELIGIBLE_BROWSER_CONTEXT_OFF_THE_RECORD = 'PrefetchNotEligibleBrowserContextOffTheRecord'

PREFETCH_NOT_ELIGIBLE_DATA_SAVER_ENABLED = 'PrefetchNotEligibleDataSaverEnabled'

PREFETCH_NOT_ELIGIBLE_EXISTING_PROXY = 'PrefetchNotEligibleExistingProxy'

PREFETCH_NOT_ELIGIBLE_HOST_IS_NON_UNIQUE = 'PrefetchNotEligibleHostIsNonUnique'

PREFETCH_NOT_ELIGIBLE_NON_DEFAULT_STORAGE_PARTITION = 'PrefetchNotEligibleNonDefaultStoragePartition'

PREFETCH_NOT_ELIGIBLE_SAME_SITE_CROSS_ORIGIN_PREFETCH_REQUIRED_PROXY = 'PrefetchNotEligibleSameSiteCrossOriginPrefetchRequiredProxy'

PREFETCH_NOT_ELIGIBLE_SCHEME_IS_NOT_HTTPS = 'PrefetchNotEligibleSchemeIsNotHttps'

PREFETCH_NOT_ELIGIBLE_USER_HAS_COOKIES = 'PrefetchNotEligibleUserHasCookies'

PREFETCH_NOT_ELIGIBLE_USER_HAS_SERVICE_WORKER = 'PrefetchNotEligibleUserHasServiceWorker'

PREFETCH_NOT_ELIGIBLE_USER_HAS_SERVICE_WORKER_NO_FETCH_HANDLER = 'PrefetchNotEligibleUserHasServiceWorkerNoFetchHandler'

PREFETCH_NOT_ELIGIBLE_REDIRECT_FROM_SERVICE_WORKER = 'PrefetchNotEligibleRedirectFromServiceWorker'

PREFETCH_NOT_ELIGIBLE_REDIRECT_TO_SERVICE_WORKER = 'PrefetchNotEligibleRedirectToServiceWorker'

PREFETCH_NOT_ELIGIBLE_BATTERY_SAVER_ENABLED = 'PrefetchNotEligibleBatterySaverEnabled'

PREFETCH_NOT_ELIGIBLE_PRELOADING_DISABLED = 'PrefetchNotEligiblePreloadingDisabled'

PREFETCH_NOT_FINISHED_IN_TIME = 'PrefetchNotFinishedInTime'

PREFETCH_NOT_STARTED = 'PrefetchNotStarted'

PREFETCH_NOT_USED_COOKIES_CHANGED = 'PrefetchNotUsedCookiesChanged'

PREFETCH_PROXY_NOT_AVAILABLE = 'PrefetchProxyNotAvailable'

PREFETCH_RESPONSE_USED = 'PrefetchResponseUsed'

PREFETCH_SUCCESSFUL_BUT_NOT_USED = 'PrefetchSuccessfulButNotUsed'

PREFETCH_NOT_USED_PROBE_FAILED = 'PrefetchNotUsedProbeFailed'

class PrerenderMismatchedHeaders(header_name, initial_value=None, activation_value=None)

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

header_name: str

initial_value: Optional[str] = None

activation_value: Optional[str] = None

Commands

Each command is a generator function. The return type Generator[x, y, z] indicates that the generator yields arguments of type x, it must be resumed with an argument of type y, and it returns type z. In this library, types x and y are the same for all commands, and z is the return type you should pay attention to. For more information, see Getting Started: Commands.

disable()

Return type:

Generator[Dict[str, Any], Dict[str, Any], None]

enable()

Return type:

Generator[Dict[str, Any], Dict[str, Any], None]

Events

Generally, you do not need to instantiate CDP events yourself. Instead, the API creates events for you and then you use the event’s attributes.

class RuleSetUpdated(rule_set)

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

rule_set: RuleSet

class RuleSetRemoved(id_)

id_: RuleSetId

class PreloadEnabledStateUpdated(disabled_by_preference, disabled_by_data_saver, disabled_by_battery_saver, disabled_by_holdback_prefetch_speculation_rules, disabled_by_holdback_prerender_speculation_rules)

Fired when a preload enabled state is updated.

disabled_by_preference: bool

disabled_by_data_saver: bool

disabled_by_battery_saver: bool

disabled_by_holdback_prefetch_speculation_rules: bool

disabled_by_holdback_prerender_speculation_rules: bool

class PrefetchStatusUpdated(key, pipeline_id, initiating_frame_id, prefetch_url, status, prefetch_status, request_id)

Fired when a prefetch attempt is updated.

key: PreloadingAttemptKey

pipeline_id: PreloadPipelineId

initiating_frame_id: FrameId

The frame id of the frame initiating prefetch.

prefetch_url: str

status: PreloadingStatus

prefetch_status: PrefetchStatus

request_id: RequestId

class PrerenderStatusUpdated(key, pipeline_id, status, prerender_status, disallowed_mojo_interface, mismatched_headers)

Fired when a prerender attempt is updated.

key: PreloadingAttemptKey

pipeline_id: PreloadPipelineId

status: PreloadingStatus

prerender_status: Optional[PrerenderFinalStatus]

disallowed_mojo_interface: Optional[str]

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.

mismatched_headers: Optional[List[PrerenderMismatchedHeaders]]

class PreloadingAttemptSourcesUpdated(loader_id, preloading_attempt_sources)

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

loader_id: LoaderId

preloading_attempt_sources: List[PreloadingAttemptSource]