jcFlexible.js的小Demo

;(function(win, lib) {
    var doc = win.document;
    var docEl = doc.documentElement;
    var metaEl = doc.querySelector('meta[name="viewport"]');
    var flexibleEl = doc.querySelector('meta[name="flexible"]');
    var dpr = 0;
    var scale = 0;
    var tid;
    var flexible = lib.flexible || (lib.flexible = {});

    if (metaEl) {
        console.warn('将根据已有的meta标签来设置缩放比例');
        var match = metaEl.getAttribute('content').match(/initial-scale=([d.]+)/);
        if (match) {
            scale = parseFloat(match[1]);
            dpr = parseInt(1 / scale);
        }
    } else if (flexibleEl) {
        var content = flexibleEl.getAttribute('content');
        if (content) {
            var initialDpr = content.match(/initial-dpr=([d.]+)/);
            var maximumDpr = content.match(/maximum-dpr=([d.]+)/);
            if (initialDpr) {
                dpr = parseFloat(initialDpr[1]);
                scale = parseFloat((1 / dpr).toFixed(2));    
            }
            if (maximumDpr) {
                dpr = parseFloat(maximumDpr[1]);
                scale = parseFloat((1 / dpr).toFixed(2));    
            }
        }
    }

    if (!dpr && !scale) {
        var isAndroid = win.navigator.appVersion.match(/android/gi);
        var isIPhone = win.navigator.appVersion.match(/iphone/gi);
        var devicePixelRatio = win.devicePixelRatio;
        if (isIPhone) {
            // iOS下，对于2和3的屏，用2倍的方案，其余的用1倍方案
            if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) {                
                dpr = 3;
            } else if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)){
                dpr = 2;
            } else {
                dpr = 1;
            }
        } else {
            // 其他设备下，仍旧使用1倍的方案
            dpr = 1;
        }
        scale = 1 / dpr;
    }

    docEl.setAttribute('data-dpr', dpr);
    if (!metaEl) {
        metaEl = doc.createElement('meta');
        metaEl.setAttribute('name', 'viewport');
        metaEl.setAttribute('content', 'initial-scale=' + scale + ', maximum-scale=' + scale + ', minimum-scale=' + scale + ', user-scalable=no');
        if (docEl.firstElementChild) {
            docEl.firstElementChild.appendChild(metaEl);
        } else {
            var wrap = doc.createElement('div');
            wrap.appendChild(metaEl);
            doc.write(wrap.innerHTML);
        }

    }

    function zoom(rem, width){
        var rate = rem/12;//0.625
        var inRate = 12/rem;//16
        var oFlexContainer = document.getElementById('flexContainer');
        oFlexContainer.style.webkitTransform = 'scale('+rate+')';
        var height = oFlexContainer.offsetHeight;
        oFlexContainer.style.width = width*inRate+'px';
        oFlexContainer.style.fontSize = 168+'px';
        oFlexContainer.style.marginLeft = -(1-rate)/2*(width*inRate) + 'px';
        oFlexContainer.style.marginTop = -(1-rate)/2*height + 'px';
        // console.log(height)
        // console.log(width*inRate)

    }
    function refreshRem(){
        var width = docEl.getBoundingClientRect().width;
        if (width / dpr > 540) {
            width = 540 * dpr;
        }
        var rem = width / 750;
        // console.log(width)
        if(document.getElementById('flexContainer')){
            var height = document.getElementById('flexContainer').getBoundingClientRect().height;
            if(rem < 12){
                zoom(rem, width, height)
            }
        }else{
            console.warn('warn：Please write ID elements for flexContainer for container!');
        }
        
        docEl.style.fontSize = rem + 'px';
        flexible.rem = win.rem = rem;
    }

    win.addEventListener('resize', function() {
        clearTimeout(tid);
        tid = setTimeout(refreshRem, 300);
    }, false);
    win.addEventListener('pageshow', function(e) {
        // if (e.persisted) {
            clearTimeout(tid);
            tid = setTimeout(refreshRem, 300);
        // }
    }, false);

    if (doc.readyState === 'complete') {
        doc.body.style.fontSize = 12 * dpr + 'px';
    } else {
        doc.addEventListener('DOMContentLoaded', function(e) {
            doc.body.style.fontSize = 12 * dpr + 'px';
        }, false);
    }
    

    refreshRem();

    flexible.dpr = win.dpr = dpr;
    flexible.refreshRem = refreshRem;
    flexible.rem2px = function(d) {
        var val = parseFloat(d) * this.rem;
        if (typeof d === 'string' && d.match(/rem$/)) {
            val += 'px';
        }
        return val;
    }
    flexible.px2rem = function(d) {
        var val = parseFloat(d) / this.rem;
        if (typeof d === 'string' && d.match(/px$/)) {
            val += 'rem';
        }
        return val;
    }
 
})(typeof window !== "undefined" ? window : this, window['lib'] || (window['lib'] = {}));

使用文档：
jcFlexible是根据手淘前端团队的flexible框架改写的一套框架，实现了不需要less编译的一套移动端样式的适配
使用须知：
1.需要引入jcFlexible.js
2.创建一个id为flexContainer的div作为container
3.所有dom元素都要写在container里面
4.所有元素都用rem代替px（以设计图为准：例如设计图为750px，一个div标注200px，则设置css为200rem）
5.可根据dpr来适配不同物理像素图片使用如下
[data-dpr="1"] .selector{

}
6.因为对元素进行了特殊处理，项目中不能用px，像素的大小和rem转化手册：
10px = 120rem
12px = 144rem
14px = 168rem
16px = 192rem
18px = 216rem
20px = 240rem
22px = 265rem
24px = 289rem
26px = 313rem
正常大小约为1px ＝ 12rem，精准几乎可以忽略不计