一、浏览器的分辨率
二、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 {
height: 900px;
}
}
@media srceen and (max:width: 480px) {
.header {
height: 400px;
}
}
@media srceen and (max:width: 350px) {
.header {
height: 300px;
}
}
三、 移动端CSS px自动转换成rem
1、px2rem-loader：将 px 自动转换成 rem
npm i px2rem-loader@0.1.9 -D
- 使用方式
const path = require('path');
module.exports = {
entry: {
index: './src/index.js',
search: './src/search.js'
},
output: {
path: path.join(__dirname, 'dist'),
filename: '[name]_[chunkhash:8].js' // JS 的文件指纹设置
},
module: {
rules: [
{
test: /.less$/,
use: [
MiniCssExtractPlugin.loader,
'css-loader',
'less-loader',
// 移动端CSS px自动转换成rem
{
loader: 'px2rem-loader',
options: {
remUnit: 75, // 1rem = 75px
remPrecision: 8 // px 转换为 rem 时小数点后的位数
}
}
]
}
]
}
}
- 打包后的 CSS 文件
2、lib-flexible：页面渲染时计算根元素的 font-size 值
可以使用手淘的 lib-flexible 库
https://github.com/amfe/lib-flexible
npm i lib-flexible@0.3.2 -S
- 将 node_modules -> lib-flexible -> flexible.js 引入到 html 文件中
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script type="text/javascript">
;(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>
- 效果展示
存在的问题：目前不支持将某些库内联到 html 里
解决：