Javascript验证允许多个文件上传的字段。检查是否有选择？ [英] Javascript validate a field that allows for multiple file upload. Check if a selection has been made?

问题描述

 < input name =uploadedfile []type = filemultiple =true/> 
  

现在，我想验证它使用JavaScript来检查文件是否被选中。我尝试了以下，但没有成功

$ p $ if（form.uploadedfile.length< 1）
{
警报（您忘记选择图像）;
返回false;
}


我知道它是一个数组，但我也试过了

  if（form.uploadedfile.value ==''）
 {
 alert（您忘记选择图片） ; 
返回false; 
} 
  

有人可以帮我解决这个问题。
谢谢

解决方案

在

 < input name =uploadedfile []id =uploadfiletype =filemultiple =true/> 
  

和JS：

  if（document.getElementById（uploadfile）。files.length <1）
 {
 alert（您忘记选择图片）; 
返回false; 
} 
  

还没有找到任何关于文件属性的信息。

I have a form that allows for multiple file uploads.

<input name="uploadedfile[]" type="file" multiple="true"/>

Now, I want to validate it using javascript to check if a file was selected. I tried the following but failed

if(form.uploadedfile.length < 1)
{
    alert("You Forgot to select an image");
    return false;
}

and I know its an array but i also tried

if(form.uploadedfile.value == '')
{
    alert("You Forgot to select an image");
    return false;
}

can someone help me out on this one. Thanks

解决方案

In this example they use a files property of the input, and check the length of that, something like this.

<input name="uploadedfile[]" id="uploadfile" type="file" multiple="true"/>

And the JS:

if(document.getElementById("uploadfile").files.length < 1)
{
   alert("You Forgot to select an image");
   return false;
}

Haven't been able to find any info about the files-property yet.

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