Drop File.html

<!DOCTYPE html>
<html>
  <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>Drop File</title>
    <style>
      #dropHere {
        display: flex;
        justify-content: center;
        align-items: center;
        margin: 5vmin auto;
        width: 50vmin;
        height: 50vmin;
        background-position: center;
        background-repeat: no-repeat;
        background-size: cover;
        border: 3px solid black;
        border-radius: 5vmin;
      }
    </style>
  </head>
  <body>
    <div id="dropHere">
      <span>↓ 拖到这儿 ↓</span>
    </div>
  </body>
  <script>
    var dropEle = document.getElementById('dropHere');
    dropEle.ondragenter = function (e) {
      return false;
    };
    dropEle.ondragover = function (e) {
      return false;
    };
    dropEle.ondrop = function (e) {
      showImage(e.dataTransfer.files[0]);
      return false;
    };
    function showImage(data) {
      var reader = new FileReader();
      reader.readAsDataURL(data);
      reader.onprogress = function (e) {
        if (e.lengthComputable) {
          dropEle.style.backgroundImage = 'url(' + e.target.result + ')';
        }
      };
    }
  </script>
</html>