rem的最新适配（淘宝）之1px像素的问题解决

• 解决了在微信上1px像素的问题，这是整体js文件，不过要自己加meta移动端头部标签，这里的rem是除以10

• 在css中直接写1px就可以了，其他的都用rem

  border: 1px solid gray;

<meta name="viewport" id="WebViewport"
        content="width=device-width,initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no" />

  (function flexible (window, document) {
    var docEl = document.documentElement
    var dpr = window.devicePixelRatio || 1
  
    // adjust body font size
    function setBodyFontSize () {
      if (document.body) {
        document.body.style.fontSize = (12 * dpr) + 'px'
      }
      else {
        document.addEventListener('DOMContentLoaded', setBodyFontSize)
      }
    }
    setBodyFontSize();
  
    // set 1rem = viewWidth / 10
    function setRemUnit () {
      var rem = docEl.clientWidth / 10
      docEl.style.fontSize = rem + 'px'
    }
  
    setRemUnit()
  
    // reset rem unit on page resize
    window.addEventListener('resize', setRemUnit)
    window.addEventListener('pageshow', function (e) {
      if (e.persisted) {
        setRemUnit()
      }
    })
  
    // detect 0.5px supports
    if (dpr >= 2) {
      var fakeBody = document.createElement('body')
      var testElement = document.createElement('div')
      testElement.style.border = '.5px solid transparent'
      fakeBody.appendChild(testElement)
      docEl.appendChild(fakeBody)
      if (testElement.offsetHeight === 1) {
        docEl.classList.add('hairlines')
      }
      docEl.removeChild(fakeBody)
    }

    var viewport = document.querySelector("meta[name=viewport]");
        var dpr = window.devicePixelRatio || 1;
        var scale = 1 / dpr;
        //下面是根据设备dpr设置viewport
        viewport.setAttribute(
            "content",
            "width=device-width,initial-scale=" +
            scale +
            ", maximum-scale=" +
            scale +
            ", minimum-scale=" +
            scale +
            ", user-scalable=no"
        );

  }(window, document))

• 这是单个的小文件，也可以兼容1px的问题

     var viewport = document.querySelector("meta[name=viewport]");
        var dpr = window.devicePixelRatio || 1;
        var scale = 1 / dpr;
        //下面是根据设备dpr设置viewport
        viewport.setAttribute(
            "content", +
            "width=device-width," +
            "initial-scale=" +
            scale +
            ", maximum-scale=" +
            scale +
            ", minimum-scale=" +
            scale +
            ", user-scalable=no"
        );
 
        var docEl = document.documentElement;
        var fontsize = 10 * (docEl.clientWidth / 750) + "px";
        docEl.style.fontSize = fontsize;