Question

如何将输入文件设置回＆＃34;没有选择文件＆＃34;如果文件格式不是图像格式？

<input type="file" name="image" id="image" value="" class="form-control" />

<script>
$("#image").change(function()
{
    var Data = document.getElementById('image');
    var FileUploadPath = Data.value;

    if (FileUploadPath != '') {
        var Extension = FileUploadPath.substring(FileUploadPath.lastIndexOf('.') + 1).toLowerCase();
        //The file uploaded is an image

        if (Extension == "gif" || Extension == "png" || Extension == "bmp"
                            || Extension == "jpeg" || Extension == "jpg"){
            return true;
        }else if (Extension != 'gif' || Extension != 'png' || Extension != 'bmp' || Extension != 'jpeg' || Extension != 'jpg') {

            alert("Photo only allows file types of GIF, PNG, JPG, JPEG and BMP. ");
            return false;
        }
    }
}); 
</script>

Answer 1

$("#image").change(function()
{
    var Data = document.getElementById('image');
    var FileUploadPath = Data.value;

    if (FileUploadPath != '') {
        var Extension = FileUploadPath.substring(FileUploadPath.lastIndexOf('.') + 1).toLowerCase();
        //The file uploaded is an image

        if (Extension == "gif" || Extension == "png" || Extension == "bmp"
                            || Extension == "jpeg" || Extension == "jpg"){
            return true;
        }else if (Extension != 'gif' || Extension != 'png' || Extension != 'bmp' || Extension != 'jpeg' || Extension != 'jpg') {

            alert("Photo only allows file types of GIF, PNG, JPG, JPEG and BMP. ");
          Data.type = '';
          Data.type = 'file';
            return false;
        }
    }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="file" name="image" id="image" value="" class="form-control" />

Answer 2

您可以将值设置为空字符串

$("#image").change(function()
{
    var Data = document.getElementById('image');
    var FileUploadPath = Data.value;

    if (FileUploadPath !== '') {
        var Extension = FileUploadPath.substring(FileUploadPath.lastIndexOf('.') + 1).toLowerCase();
        //The file uploaded is an image

if (Extension == "gif" || Extension == "png" || Extension == "bmp" || Extension == "jpeg" || Extension == "jpg"){
            return true;
        }else if (Extension != 'gif' || Extension != 'png' || Extension != 'bmp' || Extension != 'jpeg' || Extension != 'jpg') {

            alert("Photo only allows file types of GIF, PNG, JPG, JPEG and BMP. ");
			Data.value = "";
            return false;
        }
    }
});

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>File Upload</title>
</head>
<body>
<input type="file" name="image" id="image" value="" class="form-control" />	
<script src="https://code.jquery.com/jquery-3.1.0.js"></script>
</body>
</html>

如果给定的文件格式错误，请重置输入文件

2 个答案: