SweetAlert2 syntax error on Internet Explorer 11

(result) => {} is an arrow function which is completely unsupported in IE. To fix this you'll have to use a traditional anonymous function:

swal({
  // options...
}).then(function(result) {
  if (result.value) {
    swal('Deleted!', 'Your file has been deleted.', 'success');
  }
});

IE11 does not support some modern ES6 features like arrow functions and promises.

To fix it, you should either compile your code with Babel, or use a Promise-polyfill with the traditional function syntax:

swal(...)
  .then(function(result) {
    console.log(result.value)
  })

Read more about SweetAlert2 usage: https://github.com/sweetalert2/sweetalert2#usage