CODEWITHSUNDEEP
javascriptarraysnode.js
Tuan Anh Tran
Tuan Anh Tran

Reputation: 7267

Looping through a huge array in JavaScript

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?

Upvotes: 2

Views: 3515

Answers (2)

Tamas Hegedus
Tamas Hegedus

Reputation: 29946

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();
  });
}

Upvotes: 1

Steve Wellens
Steve Wellens

Reputation: 20638

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

Upvotes: 0

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