Object built-in object

object ChildProcess

child process object

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var child_process = require("child_process"); var child = child_process.spawn("ls");

inheritance relationship

#lineWidth: 1.5 #font: Helvetica,sans-Serif #fontSize: 10 #leading: 1.6 #.this: fill=lightgray #.class: fill=white [<class>object|toString();toJSON()] [<class>EventEmitter|new EventEmitter()|EventEmitter|defaultMaxListeners|on();addListener();prependListener();once();prependOnceListener();off();removeListener();removeAllListeners();setMaxListeners();getMaxListeners();listeners();listenerCount();eventNames();emit()] [<this>ChildProcess|connected;pid;exitCode;stdin;stdout;stderr;onexit;onmessage|kill();join();disconnect();send();usage()] [object] <:- [EventEmitter] [EventEmitter] <:- [ChildProcess] EventEmitter new EventEmitter() EventEmitter defaultMaxListeners on() addListener() prependListener() once() prependOnceListener() off() removeListener() removeAllListeners() setMaxListeners() getMaxListeners() listeners() listenerCount() eventNames() emit() ChildProcess connected pid exitCode stdin stdout stderr onexit onmessage kill() join() disconnect() send() usage() object toString() toJSON()

static properties

defaultMaxListeners

Integer, the default global maximum number of listeners

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static Integer ChildProcess.defaultMaxListeners;

Member properties

connected

Boolean, query whether the pipe to the child process is connected normally

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readonly Boolean ChildProcess.connected;

pid

Integer, read the id of the process pointed to by the current object

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readonly Integer ChildProcess.pid;

exitCode

Integer, query and set the exit code of the current process

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readonly Integer ChildProcess.exitCode;

stdin

Stream, read the standard input object of the process pointed to by the current object

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readonly Stream ChildProcess.stdin;

stdout

Stream, read the standard output object of the process pointed to by the current object

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readonly Stream ChildProcess.stdout;

stderr

Stream, read the standard error object of the process pointed to by the current object

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readonly Stream ChildProcess.stderr;

onexit

Function, query and bind the process exit event, equivalent to on("exit", func);

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Function ChildProcess.onexit;

onmessage

Function, query and bind subprocess message events, equivalent to on("message", func);

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Function ChildProcess.onmessage;

member function

kill

Kill the process pointed to by the current object and pass the signal

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ChildProcess.kill(Integer signal);

Call parameters:

  • signal: Integer, the signal passed

Kill the process pointed to by the current object and pass the signal

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ChildProcess.kill(String signal);

Call parameters:

  • signal: String, the passed signal

join

Wait for the process pointed to by the current object to end, and return the process end code

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ChildProcess.join() async;

Return result:

  • process end code

disconnect

close ipc pipe with child process

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ChildProcess.disconnect();

send

Send a message to the current child process

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ChildProcess.send(Value msg);

Call parameters:

  • msg: Value, specifies the message to send

usage

Query the memory occupied and the time spent by the current process

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Object ChildProcess.usage();

Return result:

  • Object, returns a report with time

The memory report produces results similar to the following:

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{ "user": 132379, "system": 50507, "rss": 8622080 }

in:

  • user returns the time the process spent in user code, in microseconds (millionths of a second)
  • system returns the time a process spent in system code, in microseconds (millionths of a second)
  • rss returns the physical memory size currently occupied by the process

on

Bind an event handler to an object

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Object ChildProcess.on(String ev, Function func);

Call parameters:

  • ev: String, specifies the name of the event
  • func: Function, specifies the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

Bind an event handler to an object

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Object ChildProcess.on(Object map);

Call parameters:

  • map: Object, specify the event mapping relationship, the object property name will be used as the event name, and the property value will be used as the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

addListener

Bind an event handler to an object

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Object ChildProcess.addListener(String ev, Function func);

Call parameters:

  • ev: String, specifies the name of the event
  • func: Function, specifies the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

Bind an event handler to an object

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Object ChildProcess.addListener(Object map);

Call parameters:

  • map: Object, specify the event mapping relationship, the object property name will be used as the event name, and the property value will be used as the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

prependListener

Bind an event handler to the object start

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Object ChildProcess.prependListener(String ev, Function func);

Call parameters:

  • ev: String, specifies the name of the event
  • func: Function, specifies the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

Bind an event handler to the object start

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Object ChildProcess.prependListener(Object map);

Call parameters:

  • map: Object, specify the event mapping relationship, the object property name will be used as the event name, and the property value will be used as the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

once

Bind a one-time event handler to the object, the one-time handler will only fire once

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Object ChildProcess.once(String ev, Function func);

Call parameters:

  • ev: String, specifies the name of the event
  • func: Function, specifies the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

Bind a one-time event handler to the object, the one-time handler will only fire once

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Object ChildProcess.once(Object map);

Call parameters:

  • map: Object, specify the event mapping relationship, the object property name will be used as the event name, and the property value will be used as the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

prependOnceListener

Bind an event handler to the object start

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Object ChildProcess.prependOnceListener(String ev, Function func);

Call parameters:

  • ev: String, specifies the name of the event
  • func: Function, specifies the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

Bind an event handler to the object start

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Object ChildProcess.prependOnceListener(Object map);

Call parameters:

  • map: Object, specify the event mapping relationship, the object property name will be used as the event name, and the property value will be used as the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

off

cancel the specified function from the object processing queue

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Object ChildProcess.off(String ev, Function func);

Call parameters:

  • ev: String, specifies the name of the event
  • func: Function, specifies the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

Cancel all functions in the object processing queue

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Object ChildProcess.off(String ev);

Call parameters:

  • ev: String, specifies the name of the event

Return result:

  • Object, returns the event object itself for easy chaining

cancel the specified function from the object processing queue

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Object ChildProcess.off(Object map);

Call parameters:

  • map: Object, specifies the event mapping relationship, the object property name is used as the event name, and the property value is used as the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

removeListener

cancel the specified function from the object processing queue

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Object ChildProcess.removeListener(String ev, Function func);

Call parameters:

  • ev: String, specifies the name of the event
  • func: Function, specifies the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

Cancel all functions in the object processing queue

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Object ChildProcess.removeListener(String ev);

Call parameters:

  • ev: String, specifies the name of the event

Return result:

  • Object, returns the event object itself for easy chaining

cancel the specified function from the object processing queue

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Object ChildProcess.removeListener(Object map);

Call parameters:

  • map: Object, specifies the event mapping relationship, the object property name is used as the event name, and the property value is used as the event handler function

Return result:

  • Object, returns the event object itself for easy chaining

removeAllListeners

Cancels all listeners for all events from the object's processing queue, or if an event is specified, removes all listeners for the specified event.

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Object ChildProcess.removeAllListeners(String ev);

Call parameters:

  • ev: String, specifies the name of the event

Return result:

  • Object, returns the event object itself for easy chaining

Cancels all listeners for all events from the object's processing queue, or if an event is specified, removes all listeners for the specified event.

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Object ChildProcess.removeAllListeners(Array evs = []);

Call parameters:

  • evs: Array, specifying the name of the event

Return result:

  • Object, returns the event object itself for easy chaining

setMaxListeners

The default limit on the number of listeners, for compatibility only

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ChildProcess.setMaxListeners(Integer n);

Call parameters:

  • n: Integer, specifies the number of events

getMaxListeners

Gets the number of default limits for listeners, for compatibility only

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Integer ChildProcess.getMaxListeners();

Return result:

  • Integer, returns the default limit number

listeners

Query the array of listeners for the specified event of the object

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Array ChildProcess.listeners(String ev);

Call parameters:

  • ev: String, specifies the name of the event

Return result:

  • Array, returns an array of listeners for the specified event

listenerCount

The number of listeners for the specified event of the query object

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Integer ChildProcess.listenerCount(String ev);

Call parameters:

  • ev: String, specifies the name of the event

Return result:

  • Integer, returns the number of listeners for the specified event

The number of listeners for the specified event of the query object

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Integer ChildProcess.listenerCount(Value o, String ev);

Call parameters:

  • o: Value, specifies the object of the query
  • ev: String, specifies the name of the event

Return result:

  • Integer, returns the number of listeners for the specified event

eventNames

Query listener event name

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Array ChildProcess.eventNames();

Return result:

  • Array, returns an array of event names

emit

Actively trigger an event

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Boolean ChildProcess.emit(String ev, ...args);

Call parameters:

  • ev: String, event name
  • args: ..., event parameters, which will be passed to the event handler

Return result:

  • Boolean, returns the event trigger status, returns true if there is a response event, otherwise returns false

toString

Returns the string representation of the object, generally returns "[Native Object]", the object can be reimplemented according to its own characteristics

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String ChildProcess.toString();

Return result:

  • String, returns the string representation of the object

toJSON

Returns the JSON format representation of the object, generally returns the set of readable properties defined by the object

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Value ChildProcess.toJSON(String key = "");

Call parameters:

  • key: String, unused

Return result:

  • Value, returns a value containing JSON serializable