round

Round a number to specific precision.

Similar: floor, ceil, round.

function round(x, pre?)
// x:   a number
// pre: to precision [1]

const xmath = require('extra-math');


xmath.round(9.135, 1);
// → 9

xmath.round(9.135, 1e-2);
// → 9.14

xmath.round(9.1357, 0.05);
// → 9.15

0.1 + 0.2
// → 0.30000000000000004 (why?)

xmath.round(0.1 + 0.2, 1e-12);
// → 0.3 (nice!)

References

• How to deal with floating point number precision in JavaScript?
• fixfloat package by @dragonwong
• float package by Michael Storgaard