Loop through Large dataset for values

Question

I am having performance issues while looping through large data sets (approx. 10k) records in Lightning component Controller using JavaScript.

Below is the object var wrpr = {Account:Account,Checked:false }; I have a list which has around 10k records of this object. While passing data to the server I need only the Account ids rather than the entire object. To accomplish this I am looping through all the elements in the list and extracting the Account Id as below. var selectedRecordIds = []; for (var i = 0; i < allRecords.length; i++) { if (allRecords[i].Checked) { selectedRecordIds.push(allRecords[i].Account.Id); } }

to execute this loop its taking around 50-60 seconds resulting in bad UI experience. Is there a better way to get the Ids from the object so that it increases the performance?

Answer 1

In JavaScript, you can simply write:

var selectedRecordIds = 
    allRecords.filter(row=>row.Checked).map(record=>record.Account.Id);

There might be something else going on, as JavaScript should require only a small fraction of a second on a modern computer to complete this task. I just tested this in a script on my browser:

var x = [];
while(x.length<1e5) {
    x.push({checked:Math.random()<0.5,account:{Id:x.length}});
}
console.log(x.filter(row=>row.checked).map(record=>record.Id));