chainable Javascript colour filter Object function prototype

filterColours.js

// Object.prototype  YMMV
const ColorOperation = {
    XOR: 'XOR',
    DIFF: 'DIFF',
    ADD: 'ADD',
    SUB: 'SUB',
    MAX: 'MAX',
    AVG: 'AVG'
};

Object.prototype.filterColours = function(tint, operation = ColorOperation.ADD) {
    function componentToHex(c) {
        const hex = c.toString(16);
        return hex.length === 1 ? "0" + hex : hex;
    }

    function hexToRgb(hex) {
        const bigint = parseInt(hex.substring(1), 16);
        const r = (bigint >> 16) & 255;
        const g = (bigint >> 8) & 255;
        const b = bigint & 255;
        return [r, g, b];
    }

    const tintRgb = hexToRgb(tint);

    for (const [key, color] of Object.entries(this)) {
        const colorRgb = hexToRgb(color);
        let newR, newG, newB;

        switch (operation) {
            case ColorOperation.ADD:
                newR = Math.min(colorRgb[0] + tintRgb[0], 255);
                newG = Math.min(colorRgb[1] + tintRgb[1], 255);
                newB = Math.min(colorRgb[2] + tintRgb[2], 255);
                break;
            case ColorOperation.SUB:
                newR = Math.max(colorRgb[0] - tintRgb[0], 0);
                newG = Math.max(colorRgb[1] - tintRgb[1], 0);
                newB = Math.max(colorRgb[2] - tintRgb[2], 0);
                break;
            case ColorOperation.XOR:
                newR = colorRgb[0] ^ tintRgb[0];
                newG = colorRgb[1] ^ tintRgb[1];
                newB = colorRgb[2] ^ tintRgb[2];
                break;
            case ColorOperation.DIFF:
                newR = Math.abs(colorRgb[0] - tintRgb[0]);
                newG = Math.abs(colorRgb[1] - tintRgb[1]);
                newB = Math.abs(colorRgb[2] - tintRgb[2]);
                break;
            case ColorOperation.MAX:
                newR = Math.max(colorRgb[0], tintRgb[0]);
                newG = Math.max(colorRgb[1], tintRgb[1]);
                newB = Math.max(colorRgb[2], tintRgb[2]);
                break;
            case ColorOperation.AVG:
                newR = Math.round((colorRgb[0] + tintRgb[0]) / 2);
                newG = Math.round((colorRgb[1] + tintRgb[1]) / 2);
                newB = Math.round((colorRgb[2] + tintRgb[2]) / 2);
                break;
        }

        const newHex = "#" + componentToHex(newR) + componentToHex(newG) + componentToHex(newB);
        this[key] = newHex;
    }

    return this;
};

const colors = {
    'physical': '#00422d', 
    'emotional': '#c0c014', 
    'intellectual': '#e94e77', 
    'spiritual': '#f97306', 
    'awareness': '#480ca8', 
    'aesthetic': '#6a0577', 
    'intuition': '#3f88c5'
};


tintColours  = { ...colors };

tintColours.filterColours("#b3889a", ColorOperation.MIN)
      .filterColours("#b3889a", ColorOperation.XOR)
      .filterColours("#b3889a", ColorOperation.AVG)
      .filterColours("#555555", ColorOperation.MIN);