replace color usage in style rules

gistfile1.txt

(function() {

    var styles, style, rules, rule, error, 
        props = ['backgroundColor', 'color'], primaryColor = 'red', replaceColor: 'blue';

    document.body.style.visibility = 'hidden';

    try {

      styles = document.styleSheets;

      for (var i = 0, len = styles.length; i < len; i++) {

        style = styles[i];

        for (var j = 0, lenj = style.cssRules.length; j < lenj; j++) {

            rule = style.cssRules[j];

          if (rule.type === CSSRule.STYLE_RULE) {

              props.forEach(function(prop) {

                  if (rule.style[prop] && rule.style[prop] == primaryColor) {
                    rule.style[prop] = replaceColor;
                  }
              });
          }
        }
      }

    } catch (error) {}

    document.body.style.visibility = '';

})();