移动端开发rem单位的格式化js文件flexible.js

来源：互联网发布：缅甸非法网络彩票赌博编辑：程序博客网时间：2024/06/10 23:04
有关前端开发的移动端适配, 借助rem可以省去很多媒体查询的工作,
对于rem, 可以在css中做一些规定, 也可以直接通过js来控制,
这样, 更是最大程度的还原了设计图.
以下代码为转载
;(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 isIPad = win.navigator.appVersion.match(/ipad/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 IsPC()     {         var userAgentInfo = navigator.userAgent;         var Agents = new Array("Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod");         var flag = true;         for (var v = 0; v < Agents.length; v++) {         if (userAgentInfo.indexOf(Agents[v]) > 0) { flag = false; break; }         }         return flag;     }    function refreshRem(){        var width = docEl.getBoundingClientRect().width;        if (IsPC() && width < 2047) {            width = width > 540 ? 540 : width;        }        var rem = width / 7.5;        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 = 14 * dpr + 'px';    } else {        doc.addEventListener('DOMContentLoaded', function(e) {            doc.body.style.fontSize = 14 * 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;    }})(window, window['lib'] || (window['lib'] = {}));
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