Home Web Front-end JS Tutorial How to control the size of uploaded files using javascript_javascript skills

How to control the size of uploaded files using javascript_javascript skills

May 16, 2016 pm 07:24 PM

复制代码 代码如下:

<form   name=Myform  onsubmit="return   CheckFileSize()">    
  <input   type=file   name=photo><br/>    
  <input   type=submit   value=submit></form>    

  <SCRIPT   LANGUAGE="JavaScript"><!--    
  function   CheckFileSize()    
  {    
      var   s   =   document.Myform.photo.value;    
      if(s==" ")return   false;    
      var   img   =   new   Image();    
      img.src   =   s;    
      alert("高   =   "    img.height       "n宽   =   "    img.width);    
      alert("fileSize   =   "    img.fileSize    "   字节");    
      return   false;    
  }    
  //--></SCRIPT>   

应用了javascript和在IE下img本身的fileSize属性。另外img还有其他的几个属性,如fileCreatedDate、fileModifiedDate、fileSize、fileUpdatedDate、filters,我们可以通过这些属性来获取图片文件的部分信息,如文件大小,我们用file表单同img标签结合,就能够在上传之前判断图片文件的大小是否合法了。
复制代码 代码如下:

<input type="text" size="4" value="10" name="fileSizeLimit" id="fileSizeLimit"/> K 
<input type="file" name="file1" id="file1" size="40" onchange="changeSrc(this)"/> 
<img src="about:blank" id="fileChecker" alt="test" height="18"/> 

<script type="text/javascript"> 
var oFileChecker = document.getElementById("fileChecker"); 

function changeSrc(filePicker) 

oFileChecker.src = filePicker.value; 


oFileChecker.onreadystatechange = function () 

if (oFileChecker.readyState == "complete") 

checkSize(); 



function checkSize() 

var limit = document.getElementById("fileSizeLimit").value * 1024; 

if (oFileChecker.fileSize > limit) 

alert("too large"); 

else 

alert("ok"); 


</script> 

复制代码 代码如下:

function   CheckFileSize()    
  {    
     var FileMaxSize = 100;//限制上传的文件大小,单位(k) 
      var   s   =   document.RegForm.Img_1.value;   
      //if(s==""){alert("No image,please select again!");document.RegForm.Img_1.focus(); return   false;}    
      var   img   =   new   Image();    

      img.src   =   s;  

     if(img.fileSize>FileMaxSize*1024){alert("The file size exceeds " FileMaxSize "K,please choose a smaller one!");document.RegForm.Img_1.focus();return false;} 

  //--></SCRIPT>    
<FORM action="**.asp" method="post" onSubmit="return CheckFileSize()" enctype="multipart/form-data" name="RegForm"> 
<input name="Next" type="submit" class="pBttn" id="Next" value="Save">

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