有没有办法限制输入类型文件中的字符数

Question

我有一个类型文件的输入，我的问题是：在我选择文件后，文件名是否可以限制为一定数量的字符？

Answer 1

You can get the file name using

var filename = document.getElementById('file-id').value;
filename = filename.replace(/^.*[\\\/]/, '');

But limitation in sense, after uploading the file you can get the file name using above approach.

Then you can have

if (filename.length < 100 ) {
  //do something
}

FYI: Evert thing happens only after the file being uploaded in client side. There is no use in limiting the filepath before uploaded to server.

Answer 2

Do you mean like this?

var limit = 8;

var fileName = document.getElementById("file-name-field").value();

// get both parts
var fileNameExtension = "." + fileName.split(".").pop();
var fileNameBase = fileName.substring(0, fileName.length()-fileNameExtension.length());

if(fileNameBase.length()>limit){
    // now limit it and set it as fileName
    fileName = fileNameBase.substring(0, limit) + fileNameExtension;
}

Answer 3

Most browsers don't allow modification of the value attribute of file fields. It's a security hole, because it would allow a malicious page to retrieve an arbitrary file using a hidden field.

Answer 4

Please try following JavaScript to check length of the file name.

function valueCheck()
{
 var filePath = document.getElementById("file").value;
 var fileName = filePath.replace(/[^\\\/]+$/, "");
    if(fileName !=null && fileName.length >10)
    {
        alert('Filename if bigger');
    }
}

Demo URL : http://jsfiddle.net/BhaveshKachhadiya/6EPvg/6/