前端移动端根据屏幕尺寸计算rem，以达到适配需求

!(function(doc, win) {

    var docEle = doc.documentElement,

        evt = ‘onorientationchange’ in window ? ‘orientationchange’ : ‘resize’,

        fn = function() {

            var width = docEle.clientWidth

            // width && (docEle.style.fontSize = 20 * (width / 375) + “px”);

            width && (docEle.style.fontSize = (10 * width) / 75 + ‘px’)

        }

    win.addEventListener(evt, fn, false)

    doc.addEventListener(‘DOMContentLoaded’, fn, false)

})(document, window)