How to use confirm using sweet alert?

Question

You will need to prevent default form behaviour on submit. After that you will need to submit form programmatically in case of Ok button is selected.

Here is how it could look like:

document.querySelector('#from1').addEventListener('submit', function(e) {
  var form = this;

  e.preventDefault(); // <--- prevent form from submitting

  swal({
      title: "Are you sure?",
      text: "You will not be able to recover this imaginary file!",
      icon: "warning",
      buttons: [
        'No, cancel it!',
        'Yes, I am sure!'
      ],
      dangerMode: true,
    }).then(function(isConfirm) {
      if (isConfirm) {
        swal({
          title: 'Shortlisted!',
          text: 'Candidates are successfully shortlisted!',
          icon: 'success'
        }).then(function() {
          form.submit(); // <--- submit form programmatically
        });
      } else {
        swal("Cancelled", "Your imaginary file is safe :)", "error");
      }
    })
});

_{UPD. Example above uses sweetalert v2.x promise API.}

Demo: http://plnkr.co/edit/YTY7PDs5Uh1XGUo9ic1s?p=preview

document.querySelector('#from1').onsubmit = function(e){

 swal({
    title: "Are you sure?",
    text: "You will not be able to recover this imaginary file!",
    type: "warning",
    showCancelButton: true,
    confirmButtonColor: '#DD6B55',
    confirmButtonText: 'Yes, I am sure!',
    cancelButtonText: "No, cancel it!",
    closeOnConfirm: false,
    closeOnCancel: false
 },
 function(isConfirm){

   if (isConfirm){
     swal("Shortlisted!", "Candidates are successfully shortlisted!", "success");

    } else {
      swal("Cancelled", "Your imaginary file is safe :)", "error");
         e.preventDefault();
    }
 });
};

You need To use then() function, like this

swal({
    title: "Are you sure?",
    text: "You will not be able to recover this imaginary file!",
    type: "warning",
    showCancelButton: true,
    confirmButtonColor: '#DD6B55',
    confirmButtonText: 'Yes, I am sure!',
    cancelButtonText: "No, cancel it!"
 }).then(
       function () { /*Your Code Here*/ },
       function () { return false; });

document.querySelector('#from1').onsubmit = function(e){

 swal({
    title: "Are you sure?",
    text: "You will not be able to recover this imaginary file!",
    type: "warning",
    showCancelButton: true,
    confirmButtonColor: '#DD6B55',
    confirmButtonText: 'Yes, I am sure!',
    cancelButtonText: "No, cancel it!",
    closeOnConfirm: false,
    closeOnCancel: false
 },
 function(isConfirm){

   if (isConfirm.value){
     swal("Shortlisted!", "Candidates are successfully shortlisted!", "success");

    } else {
      swal("Cancelled", "Your imaginary file is safe :)", "error");
         e.preventDefault();
    }
 });
};

I have been having this issue with SweetAlert2 as well. SA2 differs from 1 and puts everything inside the result object. The following above can be accomplished with the following code.

Swal.fire({
    title: 'A cool title',
    icon: 'info',
    confirmButtonText: 'Log in'
  }).then((result) => {
    if (result['isConfirmed']){
      // Put your function here
    }
  })

Everything placed inside the then result will run. Result holds a couple of parameters which can be used to do the trick. Pretty simple technique. Not sure if it works the same on SweetAlert1 but I really wouldn't know why you would choose that one above the newer version.