io.scalajs.nodejs.child_process
ChildProcess
Related Docs:
trait ChildProcess
| package child_process
io.scalajs.nodejs.child_process
Alias for emitter.on(eventName, listener).
Alias for emitter.on(eventName, listener).
emitter.addListener(eventName, listener)
on()
Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.
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 true if the event had listeners, false otherwise.
the event name
the event arguments
emitter.emit(name[, arg1][, arg2][, ...])
Spawns a shell then executes the command within that shell, buffering any generated output.
Spawns a shell then executes the command within that shell, buffering any generated output.
<String> The command to run, with space-separated arguments
the execution options
called with the output when process terminates
the ChildProcess
child_process.exec(command[, options][, callback])
Spawns a shell then executes the command within that shell, buffering any generated output.
Spawns a shell then executes the command within that shell, buffering any generated output.
<String> The command to run, with space-separated arguments
called with the output when process terminates
the ChildProcess
child_process.exec(command[, options][, callback])
Spawns a shell then executes the command within that shell, buffering any generated output.
Spawns a shell then executes the command within that shell, buffering any generated output.
<String> The command to run, with space-separated arguments
the execution options
the ChildProcess
child_process.exec(command[, options][, callback])
The child_process.fork() method is a special case of child_process.spawn() used specifically to spawn new Node.js processes.
The child_process.fork() method is a special case of child_process.spawn() used specifically to spawn new Node.js processes. Like child_process.spawn(), a ChildProcess object is returned. The returned ChildProcess will have an additional communication channel built-in that allows messages to be passed back and forth between the parent and child. See child.send() for details.
It is important to keep in mind that spawned Node.js child processes are independent of the parent with exception of the IPC communication channel that is established between the two. Each process has its own memory, with their own V8 instances. Because of the additional resource allocations required, spawning a large number of child Node.js processes is not recommended.
By default, child_process.fork() will spawn new Node.js instances using the process.execPath of the parent process. The execPath property in the options object allows for an alternative execution path to be used.
Node.js processes launched with a custom execPath will communicate with the parent process using the file descriptor (fd) identified using the environment variable NODE_CHANNEL_FD on the child process. The input and output on this fd is expected to be line delimited JSON objects.
Note: Unlike the fork(2) POSIX system call, child_process.fork() does not clone the current process.
<String> The module to run in the child
<Array> List of string arguments
the fork options
the ChildProcess
child_process.fork(modulePath[, args][, options])
Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.
Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.
emitter.getMaxListeners()
setMaxListeners()
Returns the number of listeners listening to the event named eventName.
Returns the number of listeners listening to the event named eventName.
emitter.listenerCount(eventName)
Returns a copy of the array of listeners for the event named eventName.
Returns a copy of the array of listeners for the event named eventName.
emitter.listeners(eventName)
Adds the listener function to the end of the listeners array for the event named eventName.
Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.
Returns a reference to the EventEmitter so calls can be chained.
emitter.on(eventName, listener)
Adds a one time listener function for the event named eventName.
Adds a one time listener function for the event named eventName. This listener is invoked only the next time eventName is triggered, after which it is removed.
emitter.once(eventName, listener)
Removes all listeners, or those of the specified eventName.
Removes all listeners, or those of the specified eventName.
Note that it is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).
Returns a reference to the EventEmitter so calls can be chained.
emitter.removeAllListeners([eventName])
Removes all listeners, or those of the specified eventName.
Removes all listeners, or those of the specified eventName.
Note that it is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).
Returns a reference to the EventEmitter so calls can be chained.
emitter.removeAllListeners([eventName])
Removes the specified listener from the listener array for the event named eventName.
Removes the specified listener from the listener array for the event named eventName. 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 specified eventName, then removeListener must be called multiple times to remove each instance.
Note that once an event has been emitted, all listeners attached to it at the time of emitting will be called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them from emit() in progress. Subsequent events will behave as expected.
emitter.removeListener(eventName, listener)
By default EventEmitters will print a warning if more than 10 listeners are added for a particular event.
By default EventEmitters will print a warning if more than 10 listeners are added for a particular event. This is a useful default that helps finding memory leaks. Obviously, not all events should be limited to just 10 listeners. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) for to indicate an unlimited number of listeners.
Returns a reference to the EventEmitter so calls can be chained.
emitter.setMaxListeners(n)
The child_process.spawn() method spawns a new process using the given command, with command line arguments in args.
The child_process.spawn() method spawns a new process using the given command, with command line arguments in args. If omitted, args defaults to an empty array.
<String> The command to run
<Array> List of string arguments
the spawn options
the ChildProcess
child_process.spawn(command[, args][, options])
ChildProcess Singleton