How to Safely Remove Items from a JavaScript Array While Looping?

Looping Through Arrays and Removing Items Without Breaking the Loop

In JavaScript, iterating through an array and removing elements can be tricky due to the way splice() operates. When an item is removed from an array using splice(), the array is re-indexed, which can lead to skipping over an index and an obsolete cached length.

To address this issue, there are two elegant solutions:

Decrementing the Index After Splicing

One approach is to decrement the loop index i after performing a splice(). By decrementing i, we ensure that the next iteration skips over the previously removed item, preventing any gaps in the loop.

Iterating in Reverse

Alternatively, we can iterate through the array in reverse order. Starting from the last index and decrementing i on each iteration avoids the re-indexing issue since the removed items at higher indices do not affect the lower indices. This method allows for a more efficient and cleaner loop.

Example:

Here's a revised version of the code using the reversed iteration technique:

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

This approach maintains the integrity of the loop by iterating in reverse order and handling removed items without affecting the remaining elements.

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