I'm getting response from this provider where there is a huge, deep array.
I only have to loop through this array and do some simple calculation but it's taking quite long to process.
What's the best practice to do this with JavaScript?
3
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Is that calculation always done on elements at a certain depth, or the depth varies?Hunan Rostomyan– Hunan Rostomyan2015-12-09 02:23:17 +00:00Commented Dec 9, 2015 at 2:23
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@HunanRostomyan it's done at a certain depth; say 4.Tuan Anh Tran– Tuan Anh Tran2015-12-09 02:24:00 +00:00Commented Dec 9, 2015 at 2:24
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Then loop the array for 4 times... use some counter; initialize it on the startup and then decrease it to 0 from 4.Krishna– Krishna2015-12-10 18:29:23 +00:00Commented Dec 10, 2015 at 18:29
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2 Answers
The best way to do heavy computation is to start a WebWorker. Remember that transferring large objects to a worker is slow, so you would probably like to get the response (like start an ajax) in the worker itself.
If you are stuck to one thread, you can use the following method to split the computation into smaller parts, but this will not help you if a single iteration takes too long.
function eachAsync(array, fn) {
return new Promise(function(resolve, reject) {
var index = 0;
function chunk() {
try {
var end = performance.now() + 20;
for(;;) {
if (index < array.length) {
var current = index++;
fn(array[current], current);
} else {
resolve();
break;
}
if (performance.now() >= end) {
schedule();
break;
}
}
} catch(e) {
reject(e);
}
}
function schedule() {
setTimeout(chunk, 10);
}
schedule();
});
}
Comments
If you are using HTML5 with a modern browser you can use WebWorkers: http://ejohn.org/blog/web-workers/
Or you can use a homegrown method: Execute Background Task In Javascript
4 Comments
PSWai
Since it is tagged with
node.js I believe there are more threading options for OP.
Tuan Anh Tran
@SteveWellens what is the most popular option for node.js? From what i found,
node-webworker-threads performance doesn't seem very impressive in their example.
Steve Wellens
@TuanAnhTran I don't know what the most popular option is. If they are a bit slow...who cares: they are in a background thread.
Ravi Sharma
@SteveWellens if they are in background it does not mean they can run slowly.