Question

Hi how to disable delete key press or backspace key press when deleting a particular character from a string using jQuery. For example, from string 1234-555 when the cursor is at hypen, if delete key is pressed it should not delete hypen. Instead of that cursor should stay in the same position. Basically disabling the delete key at hyphen. In the same way when the cursor is after hypen, if backspace key is pressed it should not delete hypen. Instead of that cursor should stay in the same position.

Answer 1

Sure, use the keydown event.

EDIT: to get the current position of the cursor in a text box, you will need to use the following function (provided by @CMS no less):

function getCaret(el) { 
  if (el.selectionStart) { 
    return el.selectionStart; 
  } else if (document.selection) { 
    el.focus(); 

    var r = document.selection.createRange(); 
    if (r == null) { 
      return 0; 
    } 

    var re = el.createTextRange(), 
        rc = re.duplicate(); 
    re.moveToBookmark(r.getBookmark()); 
    rc.setEndPoint('EndToStart', re); 

    return rc.text.length; 
  }  
  return 0; 
}

Now, back to my original answer:

var nobackspace = ['-'];
$(element).keydown(function(e) {
   if(e.keyCode == 8) {//backspace key was pressed
    var pos = getCaret(this);

    if(pos > 0) pos--;  //just a precaution so we don't get a negative number

    if(!jQuery.inArray($(this).val().charAt(pos), nobackspace)) return false;
   }
});

jsFiddle example