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Fetch

A domain for letting clients substitute browser's network layer with client code.

Dependencies: Network, IO, Page

Commands

Fetch.disable

Disables the fetch domain.

Fetch.enable

Enables issuing of requestPaused events. A request will be paused until client
calls one of failRequest, fulfillRequest or continueRequest/continueWithAuth.

Parameters
Name Type Description
patterns (optional) array<RequestPattern> If specified, only requests matching any of these patterns will produce
fetchRequested event and will be paused until clients response. If not set,
all requests will be affected.
handleAuthRequests (optional) boolean If true, authRequired events will be issued and requests will be paused
expecting a call to continueWithAuth.

Fetch.failRequest

Causes the request to fail with specified reason.

Parameters
Name Type Description
requestId RequestId An id the client received in requestPaused event.
errorReason Network.ErrorReason Causes the request to fail with the given reason.

Fetch.fulfillRequest

Provides response to the request.

Parameters
Name Type Description
requestId RequestId An id the client received in requestPaused event.
responseCode integer An HTTP response code.
responseHeaders (optional) array<HeaderEntry> Response headers.
binaryResponseHeaders (optional) binary Alternative way of specifying response headers as a \0-separated
series of name: value pairs. Prefer the above method unless you
need to represent some non-UTF8 values that can't be transmitted
over the protocol as text.
body (optional) binary A response body. If absent, original response body will be used if
the request is intercepted at the response stage and empty body
will be used if the request is intercepted at the request stage.
responsePhrase (optional) string A textual representation of responseCode.
If absent, a standard phrase matching responseCode is used.

Fetch.continueRequest

Continues the request, optionally modifying some of its parameters.

Parameters
Name Type Description
requestId RequestId An id the client received in requestPaused event.
url (optional) string If set, the request url will be modified in a way that's not observable by page.
method (optional) string If set, the request method is overridden.
postData (optional) binary If set, overrides the post data in the request.
headers (optional) array<HeaderEntry> If set, overrides the request headers. Note that the overrides do not
extend to subsequent redirect hops, if a redirect happens. Another override
may be applied to a different request produced by a redirect.
interceptResponse (optional) Experimental boolean If set, overrides response interception behavior for this request.

Fetch.continueWithAuth

Continues a request supplying authChallengeResponse following authRequired event.

Parameters
Name Type Description
requestId RequestId An id the client received in authRequired event.
authChallengeResponse AuthChallengeResponse Response to with an authChallenge.

Fetch.continueResponse

Experimental

Continues loading of the paused response, optionally modifying the
response headers. If either responseCode or headers are modified, all of them
must be present.

Parameters
Name Type Description
requestId RequestId An id the client received in requestPaused event.
responseCode (optional) integer An HTTP response code. If absent, original response code will be used.
responsePhrase (optional) string A textual representation of responseCode.
If absent, a standard phrase matching responseCode is used.
responseHeaders (optional) array<HeaderEntry> Response headers. If absent, original response headers will be used.
binaryResponseHeaders (optional) binary Alternative way of specifying response headers as a \0-separated
series of name: value pairs. Prefer the above method unless you
need to represent some non-UTF8 values that can't be transmitted
over the protocol as text.

Fetch.getResponseBody

Causes the body of the response to be received from the server and
returned as a single string. May only be issued for a request that
is paused in the Response stage and is mutually exclusive with
takeResponseBodyForInterceptionAsStream. Calling other methods that
affect the request or disabling fetch domain before body is received
results in an undefined behavior.
Note that the response body is not available for redirects. Requests
paused in the _redirect received_ state may be differentiated by
`responseCode` and presence of `location` response header, see
comments to `requestPaused` for details.

Parameters
Name Type Description
requestId RequestId Identifier for the intercepted request to get body for.
Return Object
Name Type Description
body string Response body.
base64Encoded boolean True, if content was sent as base64.

Fetch.takeResponseBodyAsStream

Returns a handle to the stream representing the response body.
The request must be paused in the HeadersReceived stage.
Note that after this command the request can't be continued
as is -- client either needs to cancel it or to provide the
response body.
The stream only supports sequential read, IO.read will fail if the position
is specified.
This method is mutually exclusive with getResponseBody.
Calling other methods that affect the request or disabling fetch
domain before body is received results in an undefined behavior.

Parameters
Name Type Description
requestId RequestId
Return Object
Name Type Description
stream IO.StreamHandle

Events

Fetch.requestPaused

Issued when the domain is enabled and the request URL matches the
specified filter. The request is paused until the client responds
with one of continueRequest, failRequest or fulfillRequest.
The stage of the request can be determined by presence of responseErrorReason
and responseStatusCode -- the request is at the response stage if either
of these fields is present and in the request stage otherwise.
Redirect responses and subsequent requests are reported similarly to regular
responses and requests. Redirect responses may be distinguished by the value
of `responseStatusCode` (which is one of 301, 302, 303, 307, 308) along with
presence of the `location` header. Requests resulting from a redirect will
have `redirectedRequestId` field set.

Parameters
Name Type Description
requestId RequestId Each request the page makes will have a unique id.
request Network.Request The details of the request.
frameId Page.FrameId The id of the frame that initiated the request.
resourceType Network.ResourceType How the requested resource will be used.
responseErrorReason (optional) Network.ErrorReason Response error if intercepted at response stage.
responseStatusCode (optional) integer Response code if intercepted at response stage.
responseStatusText (optional) string Response status text if intercepted at response stage.
responseHeaders (optional) array<HeaderEntry> Response headers if intercepted at the response stage.
networkId (optional) Network.RequestId If the intercepted request had a corresponding Network.requestWillBeSent event fired for it,
then this networkId will be the same as the requestId present in the requestWillBeSent event.
redirectedRequestId (optional) Experimental RequestId If the request is due to a redirect response from the server, the id of the request that
has caused the redirect.

Fetch.authRequired

Issued when the domain is enabled with handleAuthRequests set to true.
The request is paused until client responds with continueWithAuth.

Parameters
Name Type Description
requestId RequestId Each request the page makes will have a unique id.
request Network.Request The details of the request.
frameId Page.FrameId The id of the frame that initiated the request.
resourceType Network.ResourceType How the requested resource will be used.
authChallenge AuthChallenge Details of the Authorization Challenge encountered.
If this is set, client should respond with continueRequest that
contains AuthChallengeResponse.

Types

RequestId

(string)

Unique request identifier.
Note that this does not identify individual HTTP requests that are part of
a network request.

RequestStage

(string)

Stages of the request to handle. Request will intercept before the request is
sent. Response will intercept after the response is received (but before response
body is received).

Allowed Values
  • Request
  • Response

RequestPattern

(object)
Properties
Name Type Description
urlPattern (optional) string Wildcards (`'*'` -> zero or more, `'?'` -> exactly one) are allowed. Escape character is
backslash. Omitting is equivalent to `"*"`.
resourceType (optional) Network.ResourceType If set, only requests for matching resource types will be intercepted.
requestStage (optional) RequestStage Stage at which to begin intercepting requests. Default is Request.

HeaderEntry

(object)

Response HTTP header entry

Properties
Name Type Description
name string
value string

AuthChallenge

(object)

Authorization challenge for HTTP status code 401 or 407.

Properties
Name Type Description
source (optional) string Source of the authentication challenge.
origin string Origin of the challenger.
scheme string The authentication scheme used, such as basic or digest
realm string The realm of the challenge. May be empty.

AuthChallengeResponse

(object)

Response to an AuthChallenge.

Properties
Name Type Description
response string The decision on what to do in response to the authorization challenge. Default means
deferring to the default behavior of the net stack, which will likely either the Cancel
authentication or display a popup dialog box.
username (optional) string The username to provide, possibly empty. Should only be set if response is
ProvideCredentials.
password (optional) string The password to provide, possibly empty. Should only be set if response is
ProvideCredentials.

Summary