chroma-js/src/ops/premultiply.js

JavaScript library for color conversions

import Color from '../Color.js';

Color.prototype.premultiply = function (mutate = false) {
    const rgb = this._rgb;
    const a = rgb[3];
    if (mutate) {
        this._rgb = [rgb[0] * a, rgb[1] * a, rgb[2] * a, a];
        return this;
    } else {
        return new Color([rgb[0] * a, rgb[1] * a, rgb[2] * a, a], 'rgb');
    }
};