Upload file extension verification

file_extension_verification.js

$('#upload_btn').on('click', function() {
  var uploadFile = $('#upload_categories').val();
  if (!uploadFile) {
    alertify.log('请先选择文件!', 'error', 0);
    return;
  }

  var fileName = uploadFile.substr(uploadFile.lastIndexOf('\\')+1);
  var ary = ['xls', 'xlsx'];
  var suffix = uploadFile.split('.').pop().toLowerCase();
  if ($.inArray(suffix, ary) == -1) {
    alertify.log('文件类型有误，请上传excel文件!', 'error', 0);
    return;
  }

  $('#upload_category_form').submit();
});