Debugger Domain
Debugger domain exposes JavaScript debugging capabilities. It allows setting and removing breakpoints, stepping through execution, exploring stack traces, etc.
Methods
- Debugger.continueToLocation
- Debugger.disable
- Debugger.enable
- Debugger.evaluateOnCallFrame
- Debugger.getPossibleBreakpoints
- Debugger.getScriptSource
- Debugger.pause
- Debugger.removeBreakpoint
- Debugger.restartFrame
- Debugger.resume
- Debugger.searchInContent
- Debugger.setAsyncCallStackDepth
- Debugger.setBreakpoint
- Debugger.setBreakpointByUrl
- Debugger.setBreakpointsActive
- Debugger.setInstrumentationBreakpoint
- Debugger.setPauseOnExceptions
- Debugger.setScriptSource
- Debugger.setSkipAllPauses
- Debugger.setVariableValue
- Debugger.stepInto
- Debugger.stepOut
- Debugger.stepOver
- Debugger.getWasmBytecode Deprecated
- Debugger.disassembleWasmModule Experimental
- Debugger.getStackTrace Experimental
- Debugger.nextWasmDisassemblyChunk Experimental
- Debugger.setBlackboxedRanges Experimental
- Debugger.setBlackboxPatterns Experimental
- Debugger.setBreakpointOnFunctionCall Experimental
- Debugger.setReturnValue Experimental
- Debugger.pauseOnAsyncCall ExperimentalDeprecated
Events
- Debugger.breakpointResolved
- Debugger.paused
- Debugger.resumed
- Debugger.scriptFailedToParse
- Debugger.scriptParsed
Types
Methods
Debugger.continueToLocation #
Continues execution until specific location is reached.
Parameters
location
Location to continue to.
targetCallFrames
Optional
string
Allowed values: any
, current
Debugger.disable #
Disables debugger for given page.
Handles Debugger.disable request @cdp Debugger.disable If domain is already disabled, will return success.
Debugger.enable #
Enables debugger for the given page. Clients should not assume that the debugging has been enabled until the result for this command is received.
Handles Debugger.enable request @cdp Debugger.enable If domain is already enabled, will return success.
Parameters
maxScriptsCacheSize
Optional
number
The maximum size in bytes of collected scripts (not referenced by other heap objects) the debugger can hold. Puts no limit if parameter is omitted.
Return object
debuggerId
Debugger.evaluateOnCallFrame #
Evaluates expression on a given call frame.
In V8, @cdp Debugger.evaluateOnCallFrame populates the result
field with the exception value.
Parameters
callFrameId
Call frame identifier to evaluate on.
expression
string
Expression to evaluate.
objectGroup
Optional
string
String object group name to put result into (allows rapid releasing resulting object handles
using releaseObjectGroup
).
includeCommandLineAPI
Optional
boolean
Specifies whether command line API should be available to the evaluated expression, defaults to false.
silent
Optional
boolean
In silent mode exceptions thrown during evaluation are not reported and do not pause
execution. Overrides setPauseOnException
state.
returnByValue
Optional
boolean
Whether the result is expected to be a JSON object that should be sent by value.
generatePreview
Optional
boolean
Whether preview should be generated for the result.
throwOnSideEffect
Optional
boolean
Whether to throw an exception if side effect cannot be ruled out during evaluation.
timeout
Optional
Return object
result
Object wrapper for the evaluation result.
exceptionDetails
Optional
Exception details.
Debugger.getPossibleBreakpoints #
Returns possible locations for breakpoint. scriptId in start and end range locations should be the same.
Parameters
start
Start of range to search possible breakpoint locations in.
end
Optional
End of range to search possible breakpoint locations in (excluding). When not specified, end of scripts is used as end of range.
restrictToFunction
Optional
boolean
Only consider locations which are in the same (non-nested) function as start.
Return object
locations
array[ BreakLocation ]
List of the possible breakpoint locations.
Debugger.getScriptSource #
Returns source for the script with given id.
Parameters
scriptId
Id of the script to get source for.
Return object
scriptSource
string
Script source (empty in case of Wasm bytecode).
bytecode
Optional
string
Wasm bytecode. (Encoded as a base64 string when passed over JSON)
Debugger.restartFrame #
Restarts particular call frame from the beginning. The old, deprecated
behavior of restartFrame
is to stay paused and allow further CDP commands
after a restart was scheduled. This can cause problems with restarting, so
we now continue execution immediatly after it has been scheduled until we
reach the beginning of the restarted frame.
To stay back-wards compatible, restartFrame
now expects a mode
parameter to be present. If the mode
parameter is missing, restartFrame
errors out.
The various return values are deprecated and callFrames
is always empty.
Use the call frames from the Debugger#paused
events instead, that fires
once V8 pauses at the beginning of the restarted function.
Parameters
callFrameId
Call frame identifier to evaluate on.
mode
Optional
string
The mode
parameter must be present and set to 'StepInto', otherwise
restartFrame
will error out.
Allowed values: StepInto
Return object
callFrames
asyncStackTrace
Optional
asyncStackTraceId
Optional
Debugger.resume #
Resumes JavaScript execution.
Parameters
terminateOnResume
Optional
boolean
Set to true to terminate execution upon resuming execution. In contrast to Runtime.terminateExecution, this will allows to execute further JavaScript (i.e. via evaluation) until execution of the paused code is actually resumed, at which point termination is triggered. If execution is currently not paused, this parameter has no effect.
Debugger.searchInContent #
Searches for given string in script content.
Parameters
scriptId
Id of the script to search in.
query
string
String to search for.
caseSensitive
Optional
boolean
If true, search is case sensitive.
isRegex
Optional
boolean
If true, treats string parameter as regex.
Return object
result
array[ SearchMatch ]
List of search matches.
Debugger.setAsyncCallStackDepth #
Enables or disables async call stacks tracking.
Parameters
maxDepth
integer
Maximum depth of async call stacks. Setting to 0
will effectively disable collecting async
call stacks (default).
Debugger.setBreakpoint #
Sets JavaScript breakpoint at a given location.
Parameters
location
Location to set breakpoint in.
condition
Optional
string
Expression to use as a breakpoint condition. When specified, debugger will only stop on the breakpoint if this expression evaluates to true.
Return object
breakpointId
Id of the created breakpoint for further reference.
actualLocation
Location this breakpoint resolved into.
Debugger.setBreakpointByUrl #
Sets JavaScript breakpoint at given location specified either by URL or URL regex. Once this
command is issued, all existing parsed scripts will have breakpoints resolved and returned in
locations
property. Further matching script parsing will result in subsequent
breakpointResolved
events issued. This logical breakpoint will survive page reloads.
Parameters
lineNumber
integer
Line number to set breakpoint at.
url
Optional
string
URL of the resources to set breakpoint on.
urlRegex
Optional
string
Regex pattern for the URLs of the resources to set breakpoints on. Either url
or
urlRegex
must be specified.
scriptHash
Optional
string
Script hash of the resources to set breakpoint on.
columnNumber
Optional
integer
Offset in the line to set breakpoint at.
condition
Optional
string
Expression to use as a breakpoint condition. When specified, debugger will only stop on the breakpoint if this expression evaluates to true.
Return object
breakpointId
Id of the created breakpoint for further reference.
locations
array[ Location ]
List of the locations this breakpoint resolved into upon addition.
Debugger.setBreakpointsActive #
Activates / deactivates all breakpoints on the page.
Handles Debugger.setBreakpointsActive @cdp Debugger.setBreakpointsActive Allowed even if domain is not enabled.
Parameters
active
boolean
New value for breakpoints active state.
Debugger.setInstrumentationBreakpoint #
Sets instrumentation breakpoint.
Parameters
instrumentation
string
Instrumentation name.
Allowed values: beforeScriptExecution
, beforeScriptWithSourceMapExecution
Return object
breakpointId
Id of the created breakpoint for further reference.
Debugger.setPauseOnExceptions #
Defines pause on exceptions state. Can be set to stop on all exceptions, uncaught exceptions,
or caught exceptions, no exceptions. Initial pause on exceptions state is none
.
Parameters
state
string
Pause on exceptions mode.
Allowed values: none
, caught
, uncaught
, all
Debugger.setScriptSource #
Edits JavaScript source live.
In general, functions that are currently on the stack can not be edited with
a single exception: If the edited function is the top-most stack frame and
that is the only activation of that function on the stack. In this case
the live edit will be successful and a Debugger.restartFrame
for the
top-most function is automatically triggered.
Parameters
scriptId
Id of the script to edit.
scriptSource
string
New content of the script.
dryRun
Optional
boolean
If true the change will not actually be applied. Dry run may be used to get result description without actually modifying the code.
allowTopFrameEditing
Optional
boolean
If true, then scriptSource
is allowed to change the function on top of the stack
as long as the top-most stack frame is the only activation of that function.
Return object
callFrames
Optional
stackChanged
Optional
boolean
Whether current call stack was modified after applying the changes.
asyncStackTrace
Optional
asyncStackTraceId
Optional
status
string
Whether the operation was successful or not. Only Ok
denotes a
successful live edit while the other enum variants denote why
the live edit failed.
Allowed values: Ok
, CompileError
, BlockedByActiveGenerator
, BlockedByActiveFunction
, BlockedByTopLevelEsModuleChange
exceptionDetails
Optional
Exception details if any. Only present when status
is CompileError
.
Debugger.setSkipAllPauses #
Makes page not interrupt on any pauses (breakpoint, exception, dom exception etc).
Parameters
skip
boolean
New value for skip pauses state.
Debugger.setVariableValue #
Changes value of variable in a callframe. Object-based scopes are not supported and must be mutated manually.
Parameters
scopeNumber
integer
0-based number of scope as was listed in scope chain. Only 'local', 'closure' and 'catch' scope types are allowed. Other scopes could be manipulated manually.
variableName
string
Variable name.
newValue
New variable value.
callFrameId
Id of callframe that holds variable.
Debugger.stepInto #
Steps into the function call.
Parameters
breakOnAsyncCall
Optional
boolean
Debugger will pause on the execution of the first async task which was scheduled before next pause.
skipList
Optional
array[ LocationRange ]
The skipList specifies location ranges that should be skipped on step into.
Debugger.stepOver #
Steps over the statement.
Parameters
skipList
Optional
array[ LocationRange ]
The skipList specifies location ranges that should be skipped on step over.
Debugger.getWasmBytecode Deprecated#
This command is deprecated. Use getScriptSource instead.
Parameters
scriptId
Id of the Wasm script to get source for.
Return object
bytecode
string
Script source. (Encoded as a base64 string when passed over JSON)
Debugger.disassembleWasmModule Experimental#
Parameters
scriptId
Id of the script to disassemble
Return object
streamId
Optional
string
For large modules, return a stream from which additional chunks of disassembly can be read successively.
totalNumberOfLines
integer
The total number of lines in the disassembly text.
functionBodyOffsets
array[ integer
]
The offsets of all function bodies, in the format [start1, end1, start2, end2, ...] where all ends are exclusive.
chunk
The first chunk of disassembly.
Debugger.getStackTrace Experimental#
Returns stack trace with given stackTraceId
.
Parameters
stackTraceId
Return object
stackTrace
Debugger.nextWasmDisassemblyChunk Experimental#
Disassemble the next chunk of lines for the module corresponding to the stream. If disassembly is complete, this API will invalidate the streamId and return an empty chunk. Any subsequent calls for the now invalid stream will return errors.
Parameters
streamId
string
Return object
chunk
The next chunk of disassembly.
Debugger.setBlackboxedRanges Experimental#
Makes backend skip steps in the script in blackboxed ranges. VM will try leave blacklisted scripts by performing 'step in' several times, finally resorting to 'step out' if unsuccessful. Positions array contains positions where blackbox state is changed. First interval isn't blackboxed. Array should be sorted.
Parameters
scriptId
Id of the script.
positions
array[ ScriptPosition ]
Debugger.setBlackboxPatterns Experimental#
Replace previous blackbox patterns with passed ones. Forces backend to skip stepping/pausing in scripts with url matching one of the patterns. VM will try to leave blackboxed script by performing 'step in' several times, finally resorting to 'step out' if unsuccessful.
Parameters
patterns
array[ string
]
Array of regexps that will be used to check script url for blackbox state.
Debugger.setBreakpointOnFunctionCall Experimental#
Sets JavaScript breakpoint before each call to the given function. If another function was created from the same source as a given one, calling it will also trigger the breakpoint.
Parameters
objectId
Function object id.
condition
Optional
string
Expression to use as a breakpoint condition. When specified, debugger will stop on the breakpoint if this expression evaluates to true.
Return object
breakpointId
Id of the created breakpoint for further reference.
Debugger.setReturnValue Experimental#
Changes return value in top frame. Available only at return break position.
Parameters
newValue
New return value.
Debugger.pauseOnAsyncCall ExperimentalDeprecated#
Parameters
parentStackTraceId
Debugger will pause when async call with given stack trace is started.
Events
Debugger.breakpointResolved #
Fired when breakpoint is resolved to an actual script and location.
Parameters
breakpointId
Breakpoint unique identifier.
location
Actual breakpoint location.
Debugger.paused #
Fired when the virtual machine stopped on breakpoint or exception or any other stop criteria.
Although the documentation lists the "data" field as optional for the @cdp Debugger.paused event: https://chromedevtools.github.io/devtools-protocol/tot/Debugger/#event-paused it is accessed unconditionally by the front-end when the pause reason is "exception". "data" is passed in as "auxData" via: https://github.com/facebookexperimental/rn-chrome-devtools-frontend/blob/9a23d4c7c4c2d1a3d9e913af38d6965f474c4284/front_end/core/sdk/DebuggerModel.ts#L994 and "auxData" stored in a DebuggerPausedDetails instance: https://github.com/facebookexperimental/rn-chrome-devtools-frontend/blob/9a23d4c7c4c2d1a3d9e913af38d6965f474c4284/front_end/core/sdk/DebuggerModel.ts#L642 which then has its fields accessed in: https://github.com/facebookexperimental/rn-chrome-devtools-frontend/blob/main/front_end/panels/sources/DebuggerPausedMessage.ts#L225 If the "data" ("auxData") object is absent, accessing its fields will throw, breaking the display of pause information. Thus, we always populate "data" with an object. The "data" field has no schema in the protocol metadata that we use to generate message structures, so we need to manually construct a JSON object here. The structure expected by the front-end (specifically, the "description" field) can be inferred from the field access at the URL above. The front-end does gracefully handle missing fields on the "data" object, so we can consider the "description" field optional.
Parameters
callFrames
array[ CallFrame ]
Call stack the virtual machine stopped on.
reason
string
Pause reason.
Allowed values: ambiguous
, assert
, CSPViolation
, debugCommand
, DOM
, EventListener
, exception
, instrumentation
, OOM
, other
, promiseRejection
, XHR
, step
data
Optional
object
Object containing break-specific auxiliary properties.
hitBreakpoints
Optional
array[ string
]
Hit breakpoints IDs
asyncStackTrace
Optional
Async stack trace, if any.
asyncStackTraceId
Optional
asyncCallStackTraceId
Optional
Debugger.scriptFailedToParse #
Fired when virtual machine fails to parse the script.
Parameters
scriptId
Identifier of the script parsed.
url
string
URL or name of the script parsed (if any).
startLine
integer
Line offset of the script within the resource with given URL (for script tags).
startColumn
integer
Column offset of the script within the resource with given URL.
endLine
integer
Last line of the script.
endColumn
integer
Length of the last line of the script.
executionContextId
Specifies script creation context.
hash
string
Content hash of the script, SHA-256.
executionContextAuxData
Optional
object
Embedder-specific auxiliary data likely matching {isDefault: boolean, type: 'default'|'isolated'|'worker', frameId: string}
sourceMapURL
Optional
string
URL of source map associated with script (if any).
hasSourceURL
Optional
boolean
True, if this script has sourceURL.
isModule
Optional
boolean
True, if this script is ES6 module.
length
Optional
integer
This script length.
stackTrace
Optional
JavaScript top stack frame of where the script parsed event was triggered if available.
codeOffset
Optional
integer
If the scriptLanguage is WebAssembly, the code section offset in the module.
scriptLanguage
Optional
embedderName
Optional
string
The name the embedder supplied for this script.
Debugger.scriptParsed #
Fired when virtual machine parses script. This event is also fired for all known and uncollected scripts upon enabling debugger.
Parameters
scriptId
Identifier of the script parsed.
url
string
URL or name of the script parsed (if any).
startLine
integer
Line offset of the script within the resource with given URL (for script tags).
startColumn
integer
Column offset of the script within the resource with given URL.
endLine
integer
Last line of the script.
endColumn
integer
Length of the last line of the script.
executionContextId
Specifies script creation context.
hash
string
Content hash of the script, SHA-256.
executionContextAuxData
Optional
object
Embedder-specific auxiliary data likely matching {isDefault: boolean, type: 'default'|'isolated'|'worker', frameId: string}
isLiveEdit
Optional
boolean
True, if this script is generated as a result of the live edit operation.
sourceMapURL
Optional
string
URL of source map associated with script (if any).
hasSourceURL
Optional
boolean
True, if this script has sourceURL.
isModule
Optional
boolean
True, if this script is ES6 module.
length
Optional
integer
This script length.
stackTrace
Optional
JavaScript top stack frame of where the script parsed event was triggered if available.
codeOffset
Optional
integer
If the scriptLanguage is WebAssembly, the code section offset in the module.
scriptLanguage
Optional
debugSymbols
Optional
If the scriptLanguage is WebASsembly, the source of debug symbols for the module.
embedderName
Optional
string
The name the embedder supplied for this script.
Types
Debugger.BreakLocation #
Type: object
Properties
scriptId
Script identifier as reported in the Debugger.scriptParsed
.
lineNumber
integer
Line number in the script (0-based).
columnNumber
Optional
integer
Column number in the script (0-based).
type
Optional
string
Allowed values: debuggerStatement
, call
, return
Debugger.CallFrame #
JavaScript call frame. Array of call frames form the call stack.
Type: object
Properties
callFrameId
Call frame identifier. This identifier is only valid while the virtual machine is paused.
functionName
string
Name of the JavaScript function called on this call frame.
functionLocation
Optional
Location in the source code.
location
Location in the source code.
url
string
JavaScript script name or url.
Deprecated in favor of using the location.scriptId
to resolve the URL via a previously
sent Debugger.scriptParsed
event.
scopeChain
array[ Scope ]
Scope chain for this call frame.
this
this
object for this call frame.
returnValue
Optional
The value being returned, if the function is at return point.
canBeRestarted
Optional
boolean
Valid only while the VM is paused and indicates whether this frame
can be restarted or not. Note that a true
value here does not
guarantee that Debugger#restartFrame with this CallFrameId will be
successful, but it is very likely.
Debugger.DebugSymbols #
Debug symbols available for a wasm script.
Type: object
Properties
type
string
Type of the debug symbols.
Allowed values: None
, SourceMap
, EmbeddedDWARF
, ExternalDWARF
externalURL
Optional
string
URL of the external symbol source.
Debugger.Location #
Location in the source code.
Type: object
Properties
scriptId
Script identifier as reported in the Debugger.scriptParsed
.
lineNumber
integer
Line number in the script (0-based).
columnNumber
Optional
integer
Column number in the script (0-based).
Debugger.Scope #
Scope description.
Type: object
Properties
type
string
Scope type.
Allowed values: global
, local
, with
, closure
, catch
, block
, script
, eval
, module
, wasm-expression-stack
object
Object representing the scope. For global
and with
scopes it represents the actual
object; for the rest of the scopes, it is artificial transient object enumerating scope
variables as its properties.
name
Optional
string
startLocation
Optional
Location in the source code where scope starts
endLocation
Optional
Location in the source code where scope ends
Debugger.ScriptLanguage #
Enum of possible script languages.
Type: string
Allowed values: JavaScript
, WebAssembly
Debugger.SearchMatch #
Search match for resource.
Type: object
Properties
lineNumber
number
Line number in resource content.
lineContent
string
Line with match content.
Debugger.LocationRange Experimental#
Location range within one script.
Type: object
Properties
scriptId
start
end
Debugger.ScriptPosition Experimental#
Location in the source code.
Type: object
Properties
lineNumber
integer
columnNumber
integer
Debugger.WasmDisassemblyChunk Experimental#
Type: object
Properties
lines
array[ string
]
The next chunk of disassembled lines.
bytecodeOffsets
array[ integer
]
The bytecode offsets describing the start of each line.