Undefined because the test function was expecting three inputs but two only were given and function declares third as undefined. In this case, console shows room 20 undefined printed to the console. Here, we told to wait for 20 seconds, That's the reason, we see output for 20 seconds. SetTimeout(doSomething_JustOnce_AfterThisTime,20seconds): we are basically telling to do something just once after 20 seconds and the result of using this package in the above is: This is like saying to clap and stop at same time. Remember, executing these two codes one after another, it happens so quickly that we don't see any output at all. Below is the result we see if we execute above answers. SetInterval(clap_your_hands,5 seconds): we are basically telling what to do, that is, to clap once after every 5 secondsĬlearInterval(stop_clapping): we are basically telling to clear what we were doing, stop clapping task and do nothing.Īll above answers have talked about these two packages but there in one big flaw. Task: give a clap once every 5 seconds and stop doing this after 20 seconds. I am not able to clearInterval any more : clearInterval(user.intervalid) // does not work When I attach interval to an existing user object, example : user.intervalid = setInterval(test, 1000, 'room', 20) Whereas in simple Javascript it returns a simple INTEGER number The setInterval () method calls a function at specified intervals (in milliseconds). It supports the expected setInterval parameters with an extra optional one for specifying the number of repetitions to be done.This is my JS in nodeJS : function test(a, room, seconds) , So I implemented my own setInterval function which tackles the above mentioned shortcomings. On top of the previously mentioned shortcomings, I'd really appreciate if setInterval had an optional parameter for setting the number of repetitions instead of repeating infinitely. Non-number delay values are silently coerced into numbers If setTimeout () is called with delay value that's not a number, implicit type coercion is silently done on the value to convert it to a number. setTimeout only executes the callback function once after the specified duration. If for some reason, an error occurs in part of the code that is called by setInterval, it wouldn't break and keeps executing the faulty code. To call a function repeatedly (e.g., every N milliseconds), consider using setInterval (). Similar to the setTimeout function is the setInterval function. Im running a function constantly every minute. Michahell at 13:37 2 It's not number in node. Im learning node.js and just set up an empty Linux Virtual Machine and installed node. What would happen is that you'll end up with a bunch of queued requests that may not necessarily return in order. If you are using TypeScript, and you get compiler errors because somehow the NodeJS.Timer type is inferred: change to tInterval to specify you're not using node and the DOM type should be used, which is number indeed. Consider using setInterval to poll a remote server every 5 seconds, network latency, unresponsive server and other variables might prevent the request from completing on time. In some cases, the function might need longer than the interval time to finish execution. Why is setInterval evil? Doesn't care whether the callback is still running or not Despite being useful in many applications, setInterval's shortcomings could blow up your application in some circumstances. This is were the native setInterval function comes to use. If you use Javascript often you might have come across the need for delaying the execution of code within intervals of time with repetition.
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