Hack dark mode into websites

darkmode.js

function handleProp(node, prop) {
    var color = window.getComputedStyle(node)[prop];
    if(color == "rgba(0, 0, 0, 0)")
        return;
    color = color.match(/rgba?\((\d+), (\d+), (\d+)/).splice(1,3);
    if(color[0] == color[1] && color[1] == color[2]) {
        node.style[prop] = "rgb(" + (256-color[0]) + ", " + (256-color[1]) + ", " + (256-color[2]) + ")";
    }
}

function handle(node) {
    handleProp(node, 'backgroundColor');
    handleProp(node, 'color')
    handleProp(node, 'borderTopColor')
    handleProp(node, 'borderBottomColor')
    handleProp(node, 'borderLeftColor')
    handleProp(node, 'borderRightColor')
}

function trav(node) {
    handle(node);
    [].map.call(node.children, trav);
}

trav(document.body)