Problem with breaking out Jquery each loop?-Collection of common programming errors

What you are doing:

for every existing row R
  if R.id == newRow.id
    alert
    break
  else
    add newRow

This will add the newRow for each row that comes before an existing row with that id. With rows [1,2,3,4,5,6,7,8,9] and adding a row 9 will add that row 8 times before alerting “already exists”.

What you mean to do is:

exists = false
for every existing row R
  if R.id == newRow.id
    existing = true
    alert
    break

if !exists
  add newRow

Equivalent in JS:

addToTable = function() {
  var selected = $("select[name*='mySelect'] option:selected").val();
  var exists = false;
  $('#myTable').find('tr').each(function() {
    if ($(this).attr('id')==selected) { 
      alert('Record has already existed!');
      exists = true;
      return false;
    }
  });
  if(!exists) {
    $('#favourite_hotels_table').append('

‘); } }