how to load java script variable in to the bootstrap model text box as value

Try this. I think function(isConfirm) is problem.

You need use then() function

    swal({
      title: "OverTime Status!",
      text: "You Need to get Sub OT Approval " + data.value + " Hours to Time allocate in the department",
      type: "warning",
      showCancelButton: false
    }).then(function (result) {
        $('#hours_work').val(data.value);
        $('#overtime_requset').modal('show'); 
    });

For form input fields you need to use val() instead of text().

Example: $('#hours_work').val(data.value);

your posted code is bit lacking and has some errors, anyways i tried to replicate your problem and i think i may have gotten it working. Take a look at below jsfiddle snippet and see if you can implement in your code to get it working.

CHECK OUT THIS LINK FIRST: https://jsfiddle.net/b1nary/je60gxv8/2/

UPDATED WITH YOUR SWEETALERT: https://jsfiddle.net/b1nary/je60gxv8/11/

setTimeout(function() {
    swal({
    title: "OverTime Status!",
    text: "You Need to get Sub OT Approval " + data_val + " Hours to Time allocate",
    type: "warning",
    showCancelButton: true,
    confirmButtonText: "Yes, do it",
    closeOnConfirm: false,
    html: false
  }, function(){
    swal("Deleted!",
    "Poof! Your number has been added to input box!",
    "success");
    $('#hours_work').val(data_val); 
    $('#overtime_requset').modal('show');
    //clear fields    
  });

}, 1000 );