Why JavaScript’s toFixed Fails at Precise Rounding and How to Fix It

JavaScript’s built‑in toFixed cannot reliably perform true rounding due to binary floating‑point precision limits, so this article explains the underlying IEEE‑754 representation, demonstrates common pitfalls, and provides a custom rounding algorithm with code examples to achieve accurate decimal rounding.

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Why JavaScript’s toFixed Fails at Precise Rounding and How to Fix It

Beike Product & Technology

Oct 14, 2020 · Fundamentals

Understanding IEEE‑754 Floating‑Point Precision Issues in JavaScript

This article explains why JavaScript’s Number type, which follows the IEEE‑754 double‑precision standard, can produce unexpected results such as 0.1 + 0.2 = 0.30000000000000004, demonstrates the binary representation of numbers like 2.5 and 0.1, and offers practical techniques and libraries to mitigate floating‑point errors.

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Understanding IEEE‑754 Floating‑Point Precision Issues in JavaScript