2.5 KiB
Timers
Stability: 5 - Locked
All of the timer functions are globals. You do not need to require()
this module in order to use them.
setTimeout(callback, delay, [arg], [...])
To schedule execution of a one-time callback after delay milliseconds. Returns a
timeoutObject for possible use with clearTimeout(). Optionally you can
also pass arguments to the callback.
It is important to note that your callback will probably not be called in exactly
delay milliseconds - Node.js makes no guarantees about the exact timing of when
the callback will fire, nor of the ordering things will fire in. The callback will
be called as close as possible to the time specified.
clearTimeout(timeoutObject)
Prevents a timeout from triggering.
setInterval(callback, delay, [arg], [...])
To schedule the repeated execution of callback every delay milliseconds.
Returns a intervalObject for possible use with clearInterval(). Optionally
you can also pass arguments to the callback.
clearInterval(intervalObject)
Stops a interval from triggering.
unref()
The opaque value returned by setTimeout and setInterval also has the method
timer.unref() which will allow you to create a timer that is active but if
it is the only item left in the event loop won't keep the program running.
If the timer is already unrefd calling unref again will have no effect.
In the case of setTimeout when you unref you create a separate timer that
will wakeup the event loop, creating too many of these may adversely effect
event loop performance -- use wisely.
ref()
If you had previously unref()d a timer you can call ref() to explicitly
request the timer hold the program open. If the timer is already refd calling
ref again will have no effect.
setImmediate(callback, [arg], [...])
To schedule the "immediate" execution of callback after I/O events
callbacks and before setTimeout and setInterval . Returns an
immediateObject for possible use with clearImmediate(). Optionally you
can also pass arguments to the callback.
Immediates are queued in the order created, and are popped off the queue once
per loop iteration. This is different from process.nextTick which will
execute process.maxTickDepth queued callbacks per iteration. setImmediate
will yield to the event loop after firing a queued callback to make sure I/O is
not being starved. While order is preserved for execution, other I/O events may
fire between any two scheduled immediate callbacks.
clearImmediate(immediateObject)
Stops an immediate from triggering.