How to Safely Remove Array Items During Iteration in JavaScript?

Removing Array Items within a Loop: Preserving Iteration

Problem:

Iterating through an array and removing items can cause unexpected behavior when using the splice() method. As items are deleted, the array is re-indexed, potentially skipping over subsequent elements. This leads to the undefined variable error mentioned.

Solution:

There are two primary approaches to address this issue:

1. Decrementing the Loop Index: After removing an item using splice(), decrement the loop index (i--) to account for the re-indexing. This ensures the loop will continue with the correct element.
2. Reverse Iteration: Instead of iterating in ascending order (i ), iterate in reverse (i--) to avoid the effects of re-indexing. In this approach, the next item to be examined is located at a lower index than the current one, so re-indexing does not affect it.

Example:

var i = Auction.auctions.length;
while (i--) {
    ...
    if (...) {
        Auction.auctions.splice(i, 1);
    }
}

By iterating in reverse, the removal of items does not affect the next item in the iteration. Therefore, the loop continues without interruption, deleting items as desired.

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