(function(win, doc) {
    //3. 【原始宽度】  或者  【改变后的宽度】 经过换算，赋值到 html=>style=>font-size    640px 是设计稿的原始尺寸
    var fn = function(width) {
        if (width <= 1080) {
            // 手机版本
            doc.documentelement.style.fontsize = 100 * (width / 1920) + "px";
        } else {
            // pc版本
            doc.documentelement.style.fontsize = 100 * (width / 1920) + "px";
        }

        var html = document.getelementsbytagname('html')[0];
        var settedfs = parseint(html.style.fontsize);
        var realfs = parseint(window.getcomputedstyle(html).fontsize);
        var whilecount = 0;


        while (true) {
            var realfs = parseint(window.getcomputedstyle(html).fontsize);
            var delta = realfs - settedfs;
            //console.log(settedfs, realfs)
            if (math.abs(delta) != 0) //不相等
            {
                html.setattribute('style', 'font-size:' + settedfs * ((settedfs - 1) / realfs) + 'px!important');
                break;
                //settedfs/realfs 计算比实际值小n倍  然后在原基础上在放大n倍
            } else
                break;

            if (whilecount++ > 100) //为了避免死循环
                break
        }
    }


    function checkletie9() {
        var theua = window.navigator.useragent.tolowercase();
        if ((theua.match(/msie\s\d+/) && theua.match(/msie\s\d+/)[0]) || (theua.match(/trident\s?\d+/) &&
                theua.match(/trident\s?\d+/)[0])) {
            var ieversion = theua.match(/msie\s\d+/)[0].match(/\d+/)[0] || theua.match(/trident\s?\d+/)[0];
            if (ieversion <= 9) {
                return true;
                //console.log('浏览器小于ie9,请升级!')
            }
        }
        return false;
    }
    if (!checkletie9()) {
        // 1.获取 client 屏幕宽度
        var clien_width = doc.documentelement.clientwidth || doc.body.clientwidth;

        // 2.如果屏幕的宽度发生改变 触发 onresize 方法
        window.onresize = function() {
            clien_width = doc.documentelement.clientwidth || doc.body.clientwidth;
            fn(clien_width);
        }


        fn(clien_width);
    }


})(window, document);