JavaScript port of getRGBFromTemperature

colourTemperature.js

"use strict";

const clamp = (num, min, max) => num < min ? min : num > max ? max : num;

/** Given a temperature (in Kelvin), estimate an RGB equivalent
 * @param {number} tmpKelvin - Temperature (in Kelvin) between 1000 and 40000
 * @returns {{r:number, g:number, b:number}} - RGB channel intensities (0-255)
 * @description Ported from: http://www.tannerhelland.com/4435/convert-temperature-rgb-algorithm-code/
*/
exports.getRGBFromTemperature = function(tmpKelvin) {
	// All calculations require tmpKelvin \ 100, so only do the conversion once
	tmpKelvin = clamp(tmpKelvin, 1000, 40000) / 100;
	
	// Note: The R-squared values for each approximation follow each calculation
	return {
		r: tmpKelvin <= 66 ? 255 :
			clamp(329.698727446 * (Math.pow(tmpKelvin - 60, -0.1332047592)), 0, 255),  // .988
		
		g: tmpKelvin <= 66 ?
			clamp(99.4708025861 * Math.log(tmpKelvin) - 161.1195681661, 0, 255) :      // .996
			clamp(288.1221695283 * (Math.pow(tmpKelvin - 60, -0.0755148492)), 0, 255), // .987
		
		b: tmpKelvin >= 66 ? 255 : 
			tmpKelvin <= 19 ? 0 :
			clamp(138.5177312231 * Math.log(tmpKelvin - 10) - 305.0447927307, 0, 255)  // .998
	};
};