Javascript getStyle，

参考文章：

1. 设置元素浮动的几种方式

2.获取css样式表内样式的js函数currentStyle(IE),defaultView(FF)

3.JS 获取最终样式 【getStyle】

以下这个方法可以解决以上两种方法中提到的不兼容性问题

var getStyle = function(){
var f = document.defaultView;
return new Function('el', 'style', ["style.indexOf('-')>-1 && (, "float' && (, f ? 'cssFloat' : 'styleFloat', "');return el.style[style] || ", f ? 'window.getComputedStyle(el, null)[style]' : 'el.currentStyle[style]', ' || null;'].join(''));
}();

test:

function getStyleTest(){
var nav = document.getElementsByTagName("nav");
    alert(getStyle(nav[0], "margin-top"));
    alert(getStyle(nav[0], "float"));
    alert(getStyle(nav[0], "color"));
}

从RGB转化成16进制:

function getHexFromRGB(rgb){
var regexp = /^rgb\(([0-9]{0,3})\,\s([0-9]{0,3})\,\s([0-9]{0,3})\)/g;
var re = rgb.replace(regexp, "$1 $2 $3").split(" ");//利用正则表达式去掉多余的部分
    var hexColor = "#";
var hex = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'];
for (var i = 0; i < 3; i++) {
var r = null;
var c = re[i];
var hexAr = [];
while (c > 16) {
            r = c % 16;
            c = (c / 16) >> 0;
            hexAr.push(hex[r]);
        }
        hexAr.push(hex[c]);
        hexColor += hexAr.reverse().join('');
    }
return hexColor;
}

4.修改CSS规则：

参考：DOM StyleSheet Object http://www.javascriptkit.com/domref/stylesheet.shtml

<script type="text/javascript">
        window.onload = function(){
var cssRules = document.styleSheets[0].rules ? document.styleSheets[0].rules : document.styleSheets[0].cssRules;
            cssRules[1].style.fontSize = "23px";
for(var ex in cssRules[1]){
                console.log(ex);
            }
            alert(cssRules[0].type);
            alert(cssRules[0].cssText);
            alert(cssRules[0].selectorText);
        }
    </script>