（老是忘记）的屏幕适配web-移动端

第一步：安装

npm install lib-flexible

第二步：安装

npm install postcss-loader postcss-px2rem

第三步：如果是web 新建flexible.js文件。移动端可以略过此步骤进行下一步

在src下面的utils文件夹中新建  flexible.js文件，可复制粘贴：

(function() {
  // flexible.css
  var cssText =
      '' +
      '@charset "utf-8";html{color:#000;background:#fff;overflow-y:scroll;-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%;-webkit-overflow-scrolling:touch}html *{outline:0;-webkit-text-size-adjust:none;-webkit-tap-highlight-color:transparent}body,html{font-family:"Microsoft YaHei",sans-serif,Tahoma,Arial}article,aside,blockquote,body,button,code,dd,details,div,dl,dt,fieldset,figcaption,figure,footer,form,h1,h2,h3,h4,h5,h6,header,hgroup,hr,input,legend,li,menu,nav,ol,p,pre,section,td,textarea,th,ul{margin:0;padding:0;-webkit-box-sizing:border-box;-moz-box-sizing:border-box;box-sizing:border-box}article,aside,details,figcaption,figure,footer,header,hgroup,menu,nav,section{display:block}input,input[type=button],input[type=reset],input[type=submit]{resize:none;border:none;-webkit-appearance:none;border-radius:0}input,select,textarea{font-size:100%}table{border-collapse:collapse;border-spacing:0}fieldset,img{border:0}abbr,acronym{border:0;font-variant:normal}del{text-decoration:line-through}address,caption,cite,code,dfn,em,th,var{font-style:normal;font-weight:500}ol,ul{list-style:none}caption,th{text-align:left}h1,h2,h3,h4,h5,h6{font-size:100%;font-weight:500}q:after,q:before{content:\'\'}sub,sup{font-size:75%;line-height:0;position:relative;vertical-align:baseline}sup{top:-.5em}sub{bottom:-.25em}a:hover{text-decoration:underline}a,ins{text-decoration:none}a:active,a:hover,a:link,a:visited{background:0 0;-webkit-tap-highlight-color:transparent;-webkit-tap-highlight-color:transparent;outline:0;text-decoration:none}';
  // cssText end

  var styleEl = document.createElement('style');
  document.getElementsByTagName('head')[0].appendChild(styleEl);
  if (styleEl.styleSheet) {
      if (!styleEl.styleSheet.disabled) {
          styleEl.styleSheet.cssText = cssText;
      }
  } else {
      try {
          styleEl.innerHTML = cssText;
      } catch (e) {
          styleEl.innerText = cssText;
      }
  }
})();


;
(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 = width * 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'] = {}));

第四步：新建 .postcssrc.js文件 与 package.json同一路径下

在这里插入代码片设置内容：
module.exports = {
  plugins: {
    autoprefixer: {},
    'postcss-px2rem': {
      remUnit: 192 ,// PC端（1920的UI图）
      //remUnit: 75 // 移动端（750的UI图）
      propList: ['*']

    }
  }
}

第六步：在main.js中引用：新建flexible.js文件引用路径为： import ‘./utils/flexible.js’。若没有引用：import ‘lib-flexible/flexible.js’

标签：web,scale,dpr,适配,doc,var,flexible,屏幕,match
来源： https://blog.csdn.net/weixin_45102212/article/details/115703612