The inspector.Session is used for dispatching messages to the V8 inspector back-end and receiving message responses and notifications.
Node.js module
inspector/promises
class Session
- event: string | symbol,...args: any[]): void;
The
Symbol.for('nodejs.rejection')method is called in case a promise rejection happens when emitting an event andcaptureRejectionsis enabled on the emitter. It is possible to useevents.captureRejectionSymbolin place ofSymbol.for('nodejs.rejection').import { EventEmitter, captureRejectionSymbol } from 'node:events'; class MyClass extends EventEmitter { constructor() { super({ captureRejections: true }); } [captureRejectionSymbol](err, event, ...args) { console.log('rejection happened for', event, 'with', err, ...args); this.destroy(err); } destroy(err) { // Tear the resource down here. } } - event: string,listener: (...args: any[]) => void): this;
Alias for
emitter.on(eventName, listener).event: 'inspectorNotification',): this;Emitted when any notification from the V8 Inspector is received.
event: 'Runtime.executionContextCreated',): this;Issued when new execution context is created.
event: 'Runtime.executionContextDestroyed',): this;Issued when execution context is destroyed.
event: 'Runtime.executionContextsCleared',listener: () => void): this;Issued when all executionContexts were cleared in browser
event: 'Runtime.exceptionThrown',): this;Issued when exception was thrown and unhandled.
event: 'Runtime.exceptionRevoked',): this;Issued when unhandled exception was revoked.
event: 'Runtime.consoleAPICalled',): this;Issued when console API was called.
event: 'Runtime.inspectRequested',): this;Issued when object should be inspected (for example, as a result of inspect() command line API call).
event: 'Debugger.scriptParsed',): this;Fired when virtual machine parses script. This event is also fired for all known and uncollected scripts upon enabling debugger.
event: 'Debugger.scriptFailedToParse',): this;Fired when virtual machine fails to parse the script.
event: 'Debugger.breakpointResolved',): this;Fired when breakpoint is resolved to an actual script and location.
event: 'Debugger.paused',): this;Fired when the virtual machine stopped on breakpoint or exception or any other stop criteria.
event: 'Debugger.resumed',listener: () => void): this;Fired when the virtual machine resumed execution.
event: 'Console.messageAdded',): this;Issued when new console message is added.
event: 'Profiler.consoleProfileStarted',): this;Sent when new profile recording is started using console.profile() call.
event: 'Profiler.consoleProfileFinished',): this;event: 'HeapProfiler.addHeapSnapshotChunk',): this;event: 'HeapProfiler.reportHeapSnapshotProgress',): this;event: 'HeapProfiler.lastSeenObjectId',): this;If heap objects tracking has been started then backend regularly sends a current value for last seen object id and corresponding timestamp. If the were changes in the heap since last event then one or more heapStatsUpdate events will be sent before a new lastSeenObjectId event.
event: 'HeapProfiler.heapStatsUpdate',): this;If heap objects tracking has been started then backend may send update for one or more fragments
event: 'NodeTracing.dataCollected',): this;Contains an bucket of collected trace events.
event: 'NodeTracing.tracingComplete',listener: () => void): this;Signals that tracing is stopped and there is no trace buffers pending flush, all data were delivered via dataCollected events.
event: 'NodeWorker.attachedToWorker',): this;Issued when attached to a worker.
event: 'NodeWorker.detachedFromWorker',): this;Issued when detached from the worker.
event: 'NodeWorker.receivedMessageFromWorker',): this;Notifies about a new protocol message received from the session (session ID is provided in attachedToWorker notification).
event: 'Network.requestWillBeSent',): this;Fired when page is about to send HTTP request.
event: 'Network.responseReceived',): this;Fired when HTTP response is available.
event: 'Network.loadingFailed',): this;event: 'Network.loadingFinished',): this;event: 'Network.dataReceived',): this;Fired when data chunk was received over the network.
event: 'Network.webSocketCreated',): this;Fired upon WebSocket creation.
event: 'Network.webSocketClosed',): this;Fired when WebSocket is closed.
event: 'Network.webSocketHandshakeResponseReceived',): this;Fired when WebSocket handshake response becomes available.
event: 'NodeRuntime.waitingForDisconnect',listener: () => void): this;This event is fired instead of
Runtime.executionContextDestroyedwhen enabled. It is fired when the Node process finished all code execution and is waiting for all frontends to disconnect.event: 'NodeRuntime.waitingForDebugger',listener: () => void): this;This event is fired when the runtime is waiting for the debugger. For example, when inspector.waitingForDebugger is called
event: 'Target.targetCreated',): this;event: 'Target.attachedToTarget',): this; Connects a session to the inspector back-end.
Connects a session to the inspector back-end. An exception will be thrown if this API was not called on a Worker thread.
Immediately close the session. All pending message callbacks will be called with an error.
session.connect()will need to be called to be able to send messages again. Reconnected session will lose all inspector state, such as enabled agents or configured breakpoints.- emit(event: string | symbol,...args: any[]): boolean;
Synchronously calls each of the listeners registered for the event named
eventName, in the order they were registered, passing the supplied arguments to each.Returns
trueif the event had listeners,falseotherwise.import { EventEmitter } from 'node:events'; const myEmitter = new EventEmitter(); // First listener myEmitter.on('event', function firstListener() { console.log('Helloooo! first listener'); }); // Second listener myEmitter.on('event', function secondListener(arg1, arg2) { console.log(`event with parameters ${arg1}, ${arg2} in second listener`); }); // Third listener myEmitter.on('event', function thirdListener(...args) { const parameters = args.join(', '); console.log(`event with parameters ${parameters} in third listener`); }); console.log(myEmitter.listeners('event')); myEmitter.emit('event', 1, 2, 3, 4, 5); // Prints: // [ // [Function: firstListener], // [Function: secondListener], // [Function: thirdListener] // ] // Helloooo! first listener // event with parameters 1, 2 in second listener // event with parameters 1, 2, 3, 4, 5 in third listener Returns an array listing the events for which the emitter has registered listeners.
import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.on('foo', () => {}); myEE.on('bar', () => {}); const sym = Symbol('symbol'); myEE.on(sym, () => {}); console.log(myEE.eventNames()); // Prints: [ 'foo', 'bar', Symbol(symbol) ]Returns the current max listener value for the
EventEmitterwhich is either set byemitter.setMaxListeners(n)or defaults toevents.defaultMaxListeners.- eventName: string | symbol,listener?: (...args: any[]) => void): number;
Returns the number of listeners listening for the event named
eventName. Iflisteneris provided, it will return how many times the listener is found in the list of the listeners of the event.@param eventNameThe name of the event being listened for
@param listenerThe event handler function
- eventName: string | symbol): (...args: any[]) => void[];
Returns a copy of the array of listeners for the event named
eventName.server.on('connection', (stream) => { console.log('someone connected!'); }); console.log(util.inspect(server.listeners('connection'))); // Prints: [ [Function] ] - eventName: string | symbol,listener: (...args: any[]) => void): this;
Alias for
emitter.removeListener(). - on(event: string,listener: (...args: any[]) => void): this;
Adds the
listenerfunction to the end of the listeners array for the event namedeventName. No checks are made to see if thelistenerhas already been added. Multiple calls passing the same combination ofeventNameandlistenerwill result in thelistenerbeing added, and called, multiple times.server.on('connection', (stream) => { console.log('someone connected!'); });Returns a reference to the
EventEmitter, so that calls can be chained.By default, event listeners are invoked in the order they are added. The
emitter.prependListener()method can be used as an alternative to add the event listener to the beginning of the listeners array.import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.on('foo', () => console.log('a')); myEE.prependListener('foo', () => console.log('b')); myEE.emit('foo'); // Prints: // b // a@param eventThe name of the event.
@param listenerThe callback function
on(event: 'inspectorNotification',): this;Emitted when any notification from the V8 Inspector is received.
on(event: 'Runtime.executionContextsCleared',listener: () => void): this;Issued when all executionContexts were cleared in browser
on(event: 'Runtime.inspectRequested',): this;Issued when object should be inspected (for example, as a result of inspect() command line API call).
on(event: 'Debugger.scriptParsed',): this;Fired when virtual machine parses script. This event is also fired for all known and uncollected scripts upon enabling debugger.
on(event: 'Debugger.scriptFailedToParse',): this;Fired when virtual machine fails to parse the script.
on(event: 'Debugger.breakpointResolved',): this;Fired when breakpoint is resolved to an actual script and location.
on(event: 'Debugger.paused',): this;Fired when the virtual machine stopped on breakpoint or exception or any other stop criteria.
on(event: 'Debugger.resumed',listener: () => void): this;Fired when the virtual machine resumed execution.
on(event: 'Profiler.consoleProfileStarted',): this;Sent when new profile recording is started using console.profile() call.
on(event: 'HeapProfiler.lastSeenObjectId',): this;If heap objects tracking has been started then backend regularly sends a current value for last seen object id and corresponding timestamp. If the were changes in the heap since last event then one or more heapStatsUpdate events will be sent before a new lastSeenObjectId event.
on(event: 'HeapProfiler.heapStatsUpdate',): this;If heap objects tracking has been started then backend may send update for one or more fragments
on(event: 'NodeTracing.tracingComplete',listener: () => void): this;Signals that tracing is stopped and there is no trace buffers pending flush, all data were delivered via dataCollected events.
on(event: 'NodeWorker.receivedMessageFromWorker',): this;Notifies about a new protocol message received from the session (session ID is provided in attachedToWorker notification).
on(event: 'Network.webSocketHandshakeResponseReceived',): this;Fired when WebSocket handshake response becomes available.
on(event: 'NodeRuntime.waitingForDisconnect',listener: () => void): this;This event is fired instead of
Runtime.executionContextDestroyedwhen enabled. It is fired when the Node process finished all code execution and is waiting for all frontends to disconnect.on(event: 'NodeRuntime.waitingForDebugger',listener: () => void): this;This event is fired when the runtime is waiting for the debugger. For example, when inspector.waitingForDebugger is called
- once(event: string,listener: (...args: any[]) => void): this;
Adds a one-time
listenerfunction for the event namedeventName. The next timeeventNameis triggered, this listener is removed and then invoked.server.once('connection', (stream) => { console.log('Ah, we have our first user!'); });Returns a reference to the
EventEmitter, so that calls can be chained.By default, event listeners are invoked in the order they are added. The
emitter.prependOnceListener()method can be used as an alternative to add the event listener to the beginning of the listeners array.import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.once('foo', () => console.log('a')); myEE.prependOnceListener('foo', () => console.log('b')); myEE.emit('foo'); // Prints: // b // a@param eventThe name of the event.
@param listenerThe callback function
once(event: 'inspectorNotification',): this;Emitted when any notification from the V8 Inspector is received.
once(event: 'Runtime.executionContextsCleared',listener: () => void): this;Issued when all executionContexts were cleared in browser
once(event: 'Runtime.inspectRequested',): this;Issued when object should be inspected (for example, as a result of inspect() command line API call).
once(event: 'Debugger.scriptParsed',): this;Fired when virtual machine parses script. This event is also fired for all known and uncollected scripts upon enabling debugger.
once(event: 'Debugger.scriptFailedToParse',): this;Fired when virtual machine fails to parse the script.
once(event: 'Debugger.breakpointResolved',): this;Fired when breakpoint is resolved to an actual script and location.
once(event: 'Debugger.paused',): this;Fired when the virtual machine stopped on breakpoint or exception or any other stop criteria.
once(event: 'Debugger.resumed',listener: () => void): this;Fired when the virtual machine resumed execution.
once(event: 'Profiler.consoleProfileStarted',): this;Sent when new profile recording is started using console.profile() call.
once(event: 'HeapProfiler.lastSeenObjectId',): this;If heap objects tracking has been started then backend regularly sends a current value for last seen object id and corresponding timestamp. If the were changes in the heap since last event then one or more heapStatsUpdate events will be sent before a new lastSeenObjectId event.
once(event: 'HeapProfiler.heapStatsUpdate',): this;If heap objects tracking has been started then backend may send update for one or more fragments
once(event: 'NodeTracing.tracingComplete',listener: () => void): this;Signals that tracing is stopped and there is no trace buffers pending flush, all data were delivered via dataCollected events.
once(event: 'NodeWorker.receivedMessageFromWorker',): this;Notifies about a new protocol message received from the session (session ID is provided in attachedToWorker notification).
once(event: 'Network.webSocketHandshakeResponseReceived',): this;Fired when WebSocket handshake response becomes available.
once(event: 'NodeRuntime.waitingForDisconnect',listener: () => void): this;This event is fired instead of
Runtime.executionContextDestroyedwhen enabled. It is fired when the Node process finished all code execution and is waiting for all frontends to disconnect.once(event: 'NodeRuntime.waitingForDebugger',listener: () => void): this;This event is fired when the runtime is waiting for the debugger. For example, when inspector.waitingForDebugger is called
- post(method: string,params?: object): Promise<void>;
Posts a message to the inspector back-end.
import { Session } from 'node:inspector/promises'; try { const session = new Session(); session.connect(); const result = await session.post('Runtime.evaluate', { expression: '2 + 2' }); console.log(result); } catch (error) { console.error(error); } // Output: { result: { type: 'number', value: 4, description: '4' } }The latest version of the V8 inspector protocol is published on the Chrome DevTools Protocol Viewer.
Node.js inspector supports all the Chrome DevTools Protocol domains declared by V8. Chrome DevTools Protocol domain provides an interface for interacting with one of the runtime agents used to inspect the application state and listen to the run-time events.
post(method: 'Runtime.callFunctionOn',Calls function with given declaration on the given object. Object group of the result is inherited from the target object.
post(method: 'Runtime.getProperties',Returns properties of a given object. Object group of the result is inherited from the target object.
post(method: 'Runtime.releaseObjectGroup',): Promise<void>;Releases all remote objects that belong to a given group.
post(method: 'Runtime.runIfWaitingForDebugger'): Promise<void>;Tells inspected instance to run if it was waiting for debugger to attach.
post(method: 'Runtime.enable'): Promise<void>;Enables reporting of execution contexts creation by means of <code>executionContextCreated</code> event. When the reporting gets enabled the event will be sent immediately for each existing execution context.
post(method: 'Runtime.discardConsoleEntries'): Promise<void>;Discards collected exceptions and console API calls.
post(method: 'Runtime.queryObjects',post(method: 'Runtime.globalLexicalScopeNames',Returns all let, const and class variables from global scope.
post(method: '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.
post(method: 'Debugger.setBreakpointsActive',): Promise<void>;Activates / deactivates all breakpoints on the page.
post(method: 'Debugger.setSkipAllPauses',): Promise<void>;Makes page not interrupt on any pauses (breakpoint, exception, dom exception etc).
post(method: '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 <code>locations</code> property. Further matching script parsing will result in subsequent <code>breakpointResolved</code> events issued. This logical breakpoint will survive page reloads.
post(method: 'Debugger.getPossibleBreakpoints',Returns possible locations for breakpoint. scriptId in start and end range locations should be the same.
post(method: 'Debugger.continueToLocation',): Promise<void>;Continues execution until specific location is reached.
post(method: 'Debugger.setPauseOnExceptions',): Promise<void>;Defines pause on exceptions state. Can be set to stop on all exceptions, uncaught exceptions or no exceptions. Initial pause on exceptions state is <code>none</code>.
post(method: 'Debugger.setVariableValue',): Promise<void>;Changes value of variable in a callframe. Object-based scopes are not supported and must be mutated manually.
post(method: 'Debugger.setReturnValue',): Promise<void>;Changes return value in top frame. Available only at return break position.
post(method: 'Debugger.setAsyncCallStackDepth',): Promise<void>;Enables or disables async call stacks tracking.
post(method: 'Debugger.setBlackboxPatterns',): Promise<void>;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.
post(method: 'Debugger.setBlackboxedRanges',): Promise<void>;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.
post(method: 'Console.enable'): Promise<void>;Enables console domain, sends the messages collected so far to the client by means of the <code>messageAdded</code> notification.
post(method: 'Console.disable'): Promise<void>;Disables console domain, prevents further console messages from being reported to the client.
post(method: 'Profiler.setSamplingInterval',): Promise<void>;Changes CPU profiler sampling interval. Must be called before CPU profiles recording started.
post(method: 'Profiler.startPreciseCoverage',): Promise<void>;Enable precise code coverage. Coverage data for JavaScript executed before enabling precise code coverage may be incomplete. Enabling prevents running optimized code and resets execution counters.
post(method: 'Profiler.stopPreciseCoverage'): Promise<void>;Disable precise code coverage. Disabling releases unnecessary execution count records and allows executing optimized code.
post(method: 'Profiler.takePreciseCoverage'Collect coverage data for the current isolate, and resets execution counters. Precise code coverage needs to have started.
post(method: 'Profiler.getBestEffortCoverage'Collect coverage data for the current isolate. The coverage data may be incomplete due to garbage collection.
post(method: 'HeapProfiler.getObjectByHeapObjectId',post(method: 'HeapProfiler.addInspectedHeapObject',): Promise<void>;Enables console to refer to the node with given id via $x (see Command Line API for more details $x functions).
post(method: 'HeapProfiler.getHeapObjectId',post(method: 'NodeTracing.stop'): Promise<void>;Stop trace events collection. Remaining collected events will be sent as a sequence of dataCollected events followed by tracingComplete event.
post(method: 'NodeWorker.sendMessageToWorker',): Promise<void>;Sends protocol message over session with given id.
post(method: 'NodeWorker.enable',): Promise<void>;Instructs the inspector to attach to running workers. Will also attach to new workers as they start
post(method: 'NodeWorker.disable'): Promise<void>;Detaches from all running workers and disables attaching to new workers as they are started.
post(method: 'Network.disable'): Promise<void>;Disables network tracking, prevents network events from being sent to the client.
post(method: 'Network.enable'): Promise<void>;Enables network tracking, network events will now be delivered to the client.
post(method: 'Network.getRequestPostData',Returns post data sent with the request. Returns an error when no data was sent with the request.
post(method: 'Network.streamResourceContent',Enables streaming of the response for the given requestId. If enabled, the dataReceived event contains the data that was received during streaming.
post(method: 'NodeRuntime.enable'): Promise<void>;Enable the NodeRuntime events except by
NodeRuntime.waitingForDisconnect.post(method: 'NodeRuntime.notifyWhenWaitingForDisconnect',): Promise<void>;Enable the
NodeRuntime.waitingForDisconnect. - event: string,listener: (...args: any[]) => void): this;
Adds the
listenerfunction to the beginning of the listeners array for the event namedeventName. No checks are made to see if thelistenerhas already been added. Multiple calls passing the same combination ofeventNameandlistenerwill result in thelistenerbeing added, and called, multiple times.server.prependListener('connection', (stream) => { console.log('someone connected!'); });Returns a reference to the
EventEmitter, so that calls can be chained.@param eventThe name of the event.
@param listenerThe callback function
event: 'inspectorNotification',): this;Emitted when any notification from the V8 Inspector is received.
event: 'Runtime.executionContextCreated',): this;Issued when new execution context is created.
event: 'Runtime.executionContextDestroyed',): this;Issued when execution context is destroyed.
event: 'Runtime.executionContextsCleared',listener: () => void): this;Issued when all executionContexts were cleared in browser
event: 'Runtime.exceptionThrown',): this;Issued when exception was thrown and unhandled.
event: 'Runtime.exceptionRevoked',): this;Issued when unhandled exception was revoked.
event: 'Runtime.consoleAPICalled',): this;Issued when console API was called.
event: 'Runtime.inspectRequested',): this;Issued when object should be inspected (for example, as a result of inspect() command line API call).
event: 'Debugger.scriptParsed',): this;Fired when virtual machine parses script. This event is also fired for all known and uncollected scripts upon enabling debugger.
event: 'Debugger.scriptFailedToParse',): this;Fired when virtual machine fails to parse the script.
event: 'Debugger.breakpointResolved',): this;Fired when breakpoint is resolved to an actual script and location.
event: 'Debugger.paused',): this;Fired when the virtual machine stopped on breakpoint or exception or any other stop criteria.
event: 'Debugger.resumed',listener: () => void): this;Fired when the virtual machine resumed execution.
event: 'Console.messageAdded',): this;Issued when new console message is added.
event: 'Profiler.consoleProfileStarted',): this;Sent when new profile recording is started using console.profile() call.
event: 'Profiler.consoleProfileFinished',): this;event: 'HeapProfiler.addHeapSnapshotChunk',): this;event: 'HeapProfiler.reportHeapSnapshotProgress',): this;event: 'HeapProfiler.lastSeenObjectId',): this;If heap objects tracking has been started then backend regularly sends a current value for last seen object id and corresponding timestamp. If the were changes in the heap since last event then one or more heapStatsUpdate events will be sent before a new lastSeenObjectId event.
event: 'HeapProfiler.heapStatsUpdate',): this;If heap objects tracking has been started then backend may send update for one or more fragments
event: 'NodeTracing.dataCollected',): this;Contains an bucket of collected trace events.
event: 'NodeTracing.tracingComplete',listener: () => void): this;Signals that tracing is stopped and there is no trace buffers pending flush, all data were delivered via dataCollected events.
event: 'NodeWorker.attachedToWorker',): this;Issued when attached to a worker.
event: 'NodeWorker.detachedFromWorker',): this;Issued when detached from the worker.
event: 'NodeWorker.receivedMessageFromWorker',): this;Notifies about a new protocol message received from the session (session ID is provided in attachedToWorker notification).
event: 'Network.requestWillBeSent',): this;Fired when page is about to send HTTP request.
event: 'Network.responseReceived',): this;Fired when HTTP response is available.
event: 'Network.loadingFailed',): this;event: 'Network.loadingFinished',): this;event: 'Network.dataReceived',): this;Fired when data chunk was received over the network.
event: 'Network.webSocketCreated',): this;Fired upon WebSocket creation.
event: 'Network.webSocketClosed',): this;Fired when WebSocket is closed.
event: 'Network.webSocketHandshakeResponseReceived',): this;Fired when WebSocket handshake response becomes available.
event: 'NodeRuntime.waitingForDisconnect',listener: () => void): this;This event is fired instead of
Runtime.executionContextDestroyedwhen enabled. It is fired when the Node process finished all code execution and is waiting for all frontends to disconnect.event: 'NodeRuntime.waitingForDebugger',listener: () => void): this;This event is fired when the runtime is waiting for the debugger. For example, when inspector.waitingForDebugger is called
event: 'Target.targetCreated',): this;event: 'Target.attachedToTarget',): this; - event: string,listener: (...args: any[]) => void): this;
Adds a one-time
listenerfunction for the event namedeventNameto the beginning of the listeners array. The next timeeventNameis triggered, this listener is removed, and then invoked.server.prependOnceListener('connection', (stream) => { console.log('Ah, we have our first user!'); });Returns a reference to the
EventEmitter, so that calls can be chained.@param eventThe name of the event.
@param listenerThe callback function
event: 'inspectorNotification',): this;Emitted when any notification from the V8 Inspector is received.
event: 'Runtime.executionContextCreated',): this;Issued when new execution context is created.
event: 'Runtime.executionContextDestroyed',): this;Issued when execution context is destroyed.
event: 'Runtime.executionContextsCleared',listener: () => void): this;Issued when all executionContexts were cleared in browser
event: 'Runtime.exceptionThrown',): this;Issued when exception was thrown and unhandled.
event: 'Runtime.exceptionRevoked',): this;Issued when unhandled exception was revoked.
event: 'Runtime.consoleAPICalled',): this;Issued when console API was called.
event: 'Runtime.inspectRequested',): this;Issued when object should be inspected (for example, as a result of inspect() command line API call).
event: 'Debugger.scriptParsed',): this;Fired when virtual machine parses script. This event is also fired for all known and uncollected scripts upon enabling debugger.
event: 'Debugger.scriptFailedToParse',): this;Fired when virtual machine fails to parse the script.
event: 'Debugger.breakpointResolved',): this;Fired when breakpoint is resolved to an actual script and location.
event: 'Debugger.paused',): this;Fired when the virtual machine stopped on breakpoint or exception or any other stop criteria.
event: 'Debugger.resumed',listener: () => void): this;Fired when the virtual machine resumed execution.
event: 'Console.messageAdded',): this;Issued when new console message is added.
event: 'Profiler.consoleProfileStarted',): this;Sent when new profile recording is started using console.profile() call.
event: 'Profiler.consoleProfileFinished',): this;event: 'HeapProfiler.addHeapSnapshotChunk',): this;event: 'HeapProfiler.reportHeapSnapshotProgress',): this;event: 'HeapProfiler.lastSeenObjectId',): this;If heap objects tracking has been started then backend regularly sends a current value for last seen object id and corresponding timestamp. If the were changes in the heap since last event then one or more heapStatsUpdate events will be sent before a new lastSeenObjectId event.
event: 'HeapProfiler.heapStatsUpdate',): this;If heap objects tracking has been started then backend may send update for one or more fragments
event: 'NodeTracing.dataCollected',): this;Contains an bucket of collected trace events.
event: 'NodeTracing.tracingComplete',listener: () => void): this;Signals that tracing is stopped and there is no trace buffers pending flush, all data were delivered via dataCollected events.
event: 'NodeWorker.attachedToWorker',): this;Issued when attached to a worker.
event: 'NodeWorker.detachedFromWorker',): this;Issued when detached from the worker.
event: 'NodeWorker.receivedMessageFromWorker',): this;Notifies about a new protocol message received from the session (session ID is provided in attachedToWorker notification).
event: 'Network.requestWillBeSent',): this;Fired when page is about to send HTTP request.
event: 'Network.responseReceived',): this;Fired when HTTP response is available.
event: 'Network.loadingFailed',): this;event: 'Network.loadingFinished',): this;event: 'Network.dataReceived',): this;Fired when data chunk was received over the network.
event: 'Network.webSocketCreated',): this;Fired upon WebSocket creation.
event: 'Network.webSocketClosed',): this;Fired when WebSocket is closed.
event: 'Network.webSocketHandshakeResponseReceived',): this;Fired when WebSocket handshake response becomes available.
event: 'NodeRuntime.waitingForDisconnect',listener: () => void): this;This event is fired instead of
Runtime.executionContextDestroyedwhen enabled. It is fired when the Node process finished all code execution and is waiting for all frontends to disconnect.event: 'NodeRuntime.waitingForDebugger',listener: () => void): this;This event is fired when the runtime is waiting for the debugger. For example, when inspector.waitingForDebugger is called
event: 'Target.targetCreated',): this;event: 'Target.attachedToTarget',): this; - eventName: string | symbol): (...args: any[]) => void[];
Returns a copy of the array of listeners for the event named
eventName, including any wrappers (such as those created by.once()).import { EventEmitter } from 'node:events'; const emitter = new EventEmitter(); emitter.once('log', () => console.log('log once')); // Returns a new Array with a function `onceWrapper` which has a property // `listener` which contains the original listener bound above const listeners = emitter.rawListeners('log'); const logFnWrapper = listeners[0]; // Logs "log once" to the console and does not unbind the `once` event logFnWrapper.listener(); // Logs "log once" to the console and removes the listener logFnWrapper(); emitter.on('log', () => console.log('log persistently')); // Will return a new Array with a single function bound by `.on()` above const newListeners = emitter.rawListeners('log'); // Logs "log persistently" twice newListeners[0](); emitter.emit('log'); - eventName?: string | symbol): this;
Removes all listeners, or those of the specified
eventName.It is bad practice to remove listeners added elsewhere in the code, particularly when the
EventEmitterinstance was created by some other component or module (e.g. sockets or file streams).Returns a reference to the
EventEmitter, so that calls can be chained. - eventName: string | symbol,listener: (...args: any[]) => void): this;
Removes the specified
listenerfrom the listener array for the event namedeventName.const callback = (stream) => { console.log('someone connected!'); }; server.on('connection', callback); // ... server.removeListener('connection', callback);removeListener()will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specifiedeventName, thenremoveListener()must be called multiple times to remove each instance.Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any
removeListener()orremoveAllListeners()calls after emitting and before the last listener finishes execution will not remove them fromemit()in progress. Subsequent events behave as expected.import { EventEmitter } from 'node:events'; class MyEmitter extends EventEmitter {} const myEmitter = new MyEmitter(); const callbackA = () => { console.log('A'); myEmitter.removeListener('event', callbackB); }; const callbackB = () => { console.log('B'); }; myEmitter.on('event', callbackA); myEmitter.on('event', callbackB); // callbackA removes listener callbackB but it will still be called. // Internal listener array at time of emit [callbackA, callbackB] myEmitter.emit('event'); // Prints: // A // B // callbackB is now removed. // Internal listener array [callbackA] myEmitter.emit('event'); // Prints: // ABecause listeners are managed using an internal array, calling this will change the position indexes of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the
emitter.listeners()method will need to be recreated.When a single function has been added as a handler multiple times for a single event (as in the example below),
removeListener()will remove the most recently added instance. In the example theonce('ping')listener is removed:import { EventEmitter } from 'node:events'; const ee = new EventEmitter(); function pong() { console.log('pong'); } ee.on('ping', pong); ee.once('ping', pong); ee.removeListener('ping', pong); ee.emit('ping'); ee.emit('ping');Returns a reference to the
EventEmitter, so that calls can be chained. - n: number): this;
By default
EventEmitters will print a warning if more than10listeners are added for a particular event. This is a useful default that helps finding memory leaks. Theemitter.setMaxListeners()method allows the limit to be modified for this specificEventEmitterinstance. The value can be set toInfinity(or0) to indicate an unlimited number of listeners.Returns a reference to the
EventEmitter, so that calls can be chained.