pdf preview not working on html using ajax

Question

url: "http://localhost/pdfupload/php/upload.php",
    dragDrop: true,
    multiple:true,
    acceptFiles:"application/pdf*",
    allowedTypes:"pdf",
    showPreview:true,
    previewHeight: "100px",
    previewWidth: "100px",
    maxFileSize:20000*1024,
    maxFileCount:3,
    fileName: "myfile",
    returnType: "json",
    showDelete: true,
    showDownload:true,
    statusBarWidth:600,
    dragdropWidth:600,
    onSuccess:function(files,data,xhr,pd)
    {
        location.reload();
    }