JavaScript: Get all stylesheet rules

getAllStylesheetRules.js

function getAllColors() {

    for (var s in document.styleSheets) {
        var stylesheet = document.styleSheets[s];
        if (stylesheet.title == 'themecolors') {
            var rule = stylesheet.cssRules[0] || stylesheet.rules[0];

            // if (rule.style.color) {
            //     rule.style.color = "red"
            // }

            // if (rule.style.background) {
            //     rule.style.background = "black"
            // }

        }
    }
}