移动端rem布局

(function(doc, win) {
    var docEl = doc.documentElement,//设备宽度
        rem = 100, //1rem代表100px
        desW = 640, //设计稿宽度
        resizeEvt = ‘orientationchange‘ in window ? ‘orientationchange‘ : ‘resize‘,
        recalc = function() {
            var clientWidth = docEl.clientWidth;
            if (!clientWidth) return;
            if (clientWidth >= desW) {
                docEl.style.fontSize = rem + "px";
            } else {
                docEl.style.fontSize = rem * (clientWidth / desW) + ‘px‘;
            }
        };

    if (!doc.addEventListener) return;
    win.addEventListener(resizeEvt, recalc, false);
    doc.addEventListener(‘DOMContentLoaded‘, recalc, false);
})(document, window);