Run results for: toFixed vs toPrecision vs Math.round() vs Math.floorfast vs MDN round_to_precision

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.1 Safari/605.1.15

Browser: Safari 13

Operating system: Mac OS X 10.14.6

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
toFixed(4)	5864440.0 Ops/sec
toPrecision(4).toString()	5077134.5 Ops/sec
(Math.round(*10000)/10000).toString()	4707883.5 Ops/sec
Math.floor fast	12134922.0 Ops/sec
precisition round	2180206.8 Ops/sec

Script Preparation code:

var someFloat = 0.123456789;
 var round_to_precision = function (x, precision) {
    var y = +x + (precision === undefined ? 0.5 : precision/2);
    return y - (y % (precision === undefined ? 1 : +precision));
};

Tests:

toFixed(4)
someFloat.toFixed(4);
toPrecision(4).toString()
someFloat.toPrecision(4);
(Math.round(*10000)/10000).toString()
(Math.round(someFloat*10000)/10000);
Math.floor fast
~~(someFloat * 10000) / 10000;
precisition round
round_to_precision(someFloat, 4);

Run results for: toFixed vs toPrecision vs Math.round() vs Math.floorfast vs MDN round_to_precision

Added MDN round to precision function: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/round

toFixed(4)

toPrecision(4).toString()

(Math.round(*10000)/10000).toString()

Math.floor fast

precisition round