---
title: "Discussion on \"PACKED to HOLEY: How JS Arrays Fall Down the Optimization Ladder\" | Hashnode"
description: "Discussion on \"PACKED to HOLEY: How JS Arrays Fall Down the Optimization Ladder\". V8 silently profiles every array you make. One float, one string, or one hole can downgrade it forever. Here is the ladder, measured."
url: "https://hashnode.com/posts/packed-to-holey-how-js-arrays-fall-down-the-optimization-ladder/6a57b860fef462b97811386d"
---

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# [PACKED to HOLEY: How JS Arrays Fall Down the Optimization Ladder](https://malharmorey.hashnode.dev/packed-to-holey-how-js-arrays-fall-down-the-optimization-ladder?utm_source=hashnode&utm_medium=feed)

V8 silently profiles every array you make. One float, one string, or one hole can downgrade it forever. Here is the ladder, measured.

Apr 2 · 8 min read · malharmorey.hashnode.dev  
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## Written by

[Malhar Morey](https://hashnode.com/@malharmorey)

@malharmorey · Pune, India

  
[View profile](https://hashnode.com/@malharmorey)

JavaScript internals, side projects, and the bugs in between.

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