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Detailed explanation of the steps to implement file drag and drop upload using JS

php中世界最好的语言Original: 2018-05-23 10:04:502322browse

This article mainly introduces the file drag and drop upload function implemented by JS, involving javascript event triggering, dynamic modification of page element attributes and other related operating techniques. Friends in need can refer to the following

The example in this article describes the file drag and drop upload function implemented by JS. Share it with everyone for your reference, the details are as follows:

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>JS文件拖拽上传</title>
<style>
p{
 width: 300px;
 height: 300px;
 border:1px dashed #000;
 position:absolute;
 top: 50%;
 left: 50%;
 margin:-150px 0 0 -150px;
 text-align:center;
 font:20px/300px '微软雅黑';
 display:none;
}
</style>
<script>
 window.onload = function () {
  var oBox = document.getElementById('box');
  var oM = document.getElementById('m1');
  var timer = null;
  document.ondragover = function(){
   clearTimeout(timer);
   timer = setTimeout(function(){
    oBox.style.display = 'none';
   },200);
   oBox.style.display = 'block';
  };
  //进入子集的时候 会触发ondragover 频繁触发 不给ondrop机会
  oBox.ondragenter = function(){
   oBox.innerHTML = '请释放鼠标';
  };
  oBox.ondragover = function(){
   return false;
  };
  oBox.ondragleave = function(){
   oBox.innerHTML = '请将文件拖拽到此区域';
  };
  oBox.ondrop = function(ev){
   var oFile = ev.dataTransfer.files[0];
   var reader = new FileReader();
   //读取成功
   reader.onload = function(){
    console.log(reader);
   };
   reader.onloadstart = function(){
    alert('读取开始');
   };
   reader.onloadend = function(){
    alert('读取结束');
   };
   reader.onabort = function(){
    alert('中断');
   };
   reader.onerror = function(){
    alert('读取失败');
   };
   reader.onprogress = function(ev){
    var scale = ev.loaded/ev.total;
    if(scale>=0.5){
     alert(1);
     reader.abort();
    }
    oM.value = scale*100;
   };
   reader.readAsDataURL(oFile,'base64');
   return false;
  };
 };
</script>
</head>
<body>
<meter id="m1" value="0" min="0" max="100"></meter>
 <p id="box">请将文件拖拽到此区域</p>
</body>
</html>

Use http://tools.jb51.net/code/HtmlJsRun to run the test online and the results are as follows:

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

Detailed explanation of the steps to implement file drag and drop upload using JS

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