The Leaderboard Arrived Sorted. JavaScript Re-sorted It by User ID.
Why JavaScript object key order puts integer-like keys first in ascending order, how that silently reorders JSON from your API, and when to use an array or Map.
5 min read
Understand JavaScript, React & Next.js — one short post at a time.
Practical, diagram-first explanations you can read over coffee. 53 posts and counting.
Newest
The $4.35 Item That Was Charged $4.34
Why 0.1 + 0.2 !== 0.3 in JavaScript, how floating-point math drops a cent when converting dollars to cents, and why money should be stored as integers.
5 min read
Latest
All 53 posts →Scrolling My Blog Index Prefetched All 51 Posts. One Config Line Cut It to 90 kB.
What a long list of Next.js <Link>s really costs in prefetch requests, measured on this blog, and how partialPrefetching shares one App Shell per route instead.
4 min read
The Server Action That Ran Twice, but Only on localhost
Why a Next.js Server Action called from useEffect runs twice in development: React Strict Mode mounts every component twice. What that reveals, and where the call belongs.
4 min read
The Settings Object That Came Back undefined
How automatic semicolon insertion (ASI) turns `return` followed by a newline into `return;`, and the lines where JavaScript refuses to add a semicolon at all.
5 min read
You Selected Rows 3, 8, 12, 15 and 20. JavaScript Checked 3, 1 and 8.
Why ['1', '7', '11'].map(parseInt) returns [1, NaN, 3]: map passes the index as parseInt's radix. Plus the Number('') trap hiding in the obvious fix.
4 min read2
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