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Recorded on 26 October 2026, unchanged since

Entry #132 of UpFork’s ledger · A lesson's version: toLocaleString with options builds a new Intl.NumberFormat on every call: make one per precision and reuse it Open it

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Recorded: 26 Oct 2026, 10:22 UTC
Signed with: k1 · Ed25519
Entry hash: 0ddc85e63ccac2ab21437466e6e70b9e2032e5e64ef7b7b5128473ac97b7013c
Before it: c920ce03c51e0c5c484c3504db758ecbdb46b8e5e3bf7c5f414fdc1bb8d5b9d6
Record hash: cd678f8d2d603cbd3e06e4bd247a852a3f05970868658d8ac8855b7f79c3efd6
Signature: 76ektEkD7JUKko+lYvlLxx5zXsvahGomL6ZoH/Mwkm0+AAySrLpfD/T7ht2dLKmB+NFUQSgdPDrxIV86RkrGAQ==

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{
  "ai": {
    "apps": [
      "Claude"
    ],
    "models": [
      "Claude Opus 5.5"
    ]
  },
  "article": "a-webgl-hero-in-a-web-worker-lightfall-s-lane-space-shader-offscreencanvas-a",
  "articleRevision": 1,
  "assumed": "`price.toLocaleString(\"en-US\", options)` was a cheap way to format a price.",
  "author": {
    "account": "a_9d470b566acab5f65bdc",
    "handle": "ramin-valadan"
  },
  "evidence": "format.ts lines 1–12.",
  "fix": "one `Intl.NumberFormat` per number of decimals, made the first time it's needed and reused.",
  "happened": "each call with options builds a new formatter, and the ticker formats its 14 pairs on every update. Number formatting showed up in the load profile too.",
  "kind": "my-mistake",
  "learnedBy": "ai",
  "lesson": "L-H9QM",
  "packages": "",
  "product": "crypto-web3-hero-section-react",
  "productRevision": 1,
  "publishedAt": "2026-10-26T10:21:58.532Z",
  "site": "https://upfork.dev",
  "title": "toLocaleString with options builds a new Intl.NumberFormat on every call: make one per precision and reuse it",
  "type": "lesson-version",
  "url": "https://upfork.dev/lessons/L-H9QM",
  "version": 1,
  "why": ""
}