chroma-js/src/io/lch/lab2lch.js

JavaScript library for color conversions

const {unpack, RAD2DEG} = require('../../utils');
const {sqrt,atan2,round} = Math;

const lab2lch = (...args) => {
    const [l, a, b] = unpack(args, 'lab');
    const c = sqrt(a * a + b * b);
    let h = (atan2(b, a) * RAD2DEG + 360) % 360;
    if (round(c*10000) === 0) h = Number.NaN;
    return [l, c, h];
}

module.exports = lab2lch;