Multi tool use

How to implement setTimeout before blocking while in nodeJS

I have blocking code like this:

let a = 0;
setTimeout(() => {
console.log(a);
process.exit();
}, 1000);


while (true) {
a++;
}


How can I use nexttick function to unblock timeout? Or somethink like this to implement setTimeout before blocking while?

nexttick

while

2 Answers
2

The callback you register in setTimeout will never be called, since you're blocking the main thread.

You could setInterval to achieve something similar, e.g.

let a = 2;
setTimeout(() => {
console.log(a);
process.exit();
}, 1000);

setInterval(() => {
// Square a
a = a * a;
}, 200);


Blocking the main thread isn't really a good idea in Node! There's usually a better way to do things in an asynchronous way.

a = a * a;

Node gets locked when you run synchronous code, meaning if you have a long-running loop it may be helpful to structure it in an asynchronous way so it becomes non-blocking.

while(true) {
doSomeSyncronousStuff();
}


should become something like

let someDelay = 0;
let loop = function(continueRunning){
doSomeSyncronousStuff();
if(continueRunning) {
// delay of as little as 0 pushes execution to at least next tick
setTimeout(loop,someDelay,continueRunning);
}
};
loop(true);


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