/*
作者：淡新举
联系：http://www.scriptlover.com
功能：使元素fixed定位
*/
var fixedPosition = function(element, top, left) {
    element.style.display = "block";
    if (!window.XMLHttpRequest && window.ActiveXObject) {
        element.style.position = "absolute";
        fixedPosition.setGlobal();
    }
    else {
        element.style.position = "fixed";
    }
    element.style.top = top + "px";
    element.style.left = left + "px";
};

/*添加css规则*/
fixedPosition.addCSSRule = function(key, value) {
    var css = document.styleSheets[document.styleSheets.length - 1];
    css.cssRules ?
		 (css.insertRule(key + "{" + value + "}", css.cssRules.length)) :
		 (css.addRule(key, value));

};

/*标志特定公共规则是否存在*/
fixedPosition.inited = false;

/*设置特定公共规则*/
fixedPosition.setGlobal = function() {
    if (!fixedPosition.inited) {
        document.body.style.height = "100%";
        document.body.style.overflow = "auto";
        fixedPosition.addCSSRule("*html", "overflow-x:auto;overflow-y:hidden;");
        fixedPosition.inited = true;
    }
};