说明
玩转webpack课程学习笔记。
浏览器的分辨率
CSS 媒体查询实现响应式布局
缺陷：需要写多套适配样式代码
@media screen and (max-width: 980px) { .header { width: 900px; } } @media screen and (max-width: 480px) { .header { height: 400px; } } @media screen and (max-width: 350px) { .header { height: 300px; } }
rem 是什么
W3C 对 rem 的定义： font-size of the root element。
- rem 是相对单位
- px 是绝对单位
移动端 CSS px 自动转换成 rem
1、使用 px2rem-loader
npm i px2rem-loader -D
2、页面渲染时计算根元素的 font-size 值
npm i lib-flexible -S
3、手动添加flexible
找到node_modules\lib-flexible\flexible.js，复制到search.html文件里面
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> <script> ;(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 refreshRem(){ var width = docEl.getBoundingClientRect().width; if (width / dpr > 540) { width = 540 * dpr; } var rem = width / 10; 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; } })(window, window['lib'] || (window['lib'] = {})); </script> </head> <body> <div id="root"></div> </body> </html>
5、不转化怎么处理
后面有
/*no*/这种注释语法会不进行 rem 的转换
@font-face{ font-family: 'SourceHanSerifSC-Heavy'; src: url('./fonts/SourceHanSerifSC-Heavy.otf') format('truetype'); } .search-text { font-size: 43px; width: 200px; /* no */ color: green; font-family: 'SourceHanSerifSC-Heavy'; display: flex; }
6、效果
