187650 2018-07-13 11:16:43 -0700 Number.toPrecision returns a wrong value 2021-05-06 17:46:26 -0700 1 1 1 Unclassified WebKit JavaScriptCore Safari 11 Unspecified Unspecified RESOLVED WONTFIX P2 Normal --- 1 isol2 webkit-unassigned ashvayka oldest_to_newest 1441926 0 isol2 2018-07-13 11:16:43 -0700 Version: JavaScriptCore v233804 OS: Ubuntu 16.04 x64 Hi everyone, I found an issue on a test case using Number.toPrecision that I don’t know if it is considered as an incompatibility issue between engines or a real bug example, but according with ES6 specs some values are described as "approximately" maybe this is a case of it. V8, JSC and SpiderMonkey returns the wrong value if param > 17, only Chakra works as expected. Steps to reproduce: print(123.56.toPrecision(18) === "123.560000000000000"); print(123.56.toPrecision(18)) Actual results: False 123.560000000000002 Expected results: True 123.560000000000000 1757750 1 ashvayka 2021-05-06 17:46:26 -0700 (In reply to isol2 from comment #0) > I found an issue on a test case using Number.toPrecision that I don’t know > if it is considered as an incompatibility issue between engines or a real > bug example, but according with ES6 specs some values are described as > "approximately" maybe this is a case of it. Thank you for report! This is most certainly a IEEE 754 precision issue like 0.1 + 0.2 != 0.3. The spec prose is worded to highlight the inaccuracy: please see step 10.a of https://tc39.es/ecma262/#sec-number.prototype.toprecision.