JavaScript/jQuery – Add a character at the end of an input field

Question

I'm trying to make an input field which automatically puts a questionmark at the end of the typed text while typing.

I just came up with this code but obviously it generates multiple questionmarks.

$("#id").keyup(function(){
   $(this).val($(this).val() + "?");
});

Thank you for your ideas.

How would the code differentiate a question mark the user entered from one the script appended? In other words, how would you know when someone is done typing if you're checking after every character? — j08691, Jun 01 '12 at 19:02

qwertymk · Accepted Answer · 2012-06-01T19:03:54.803

8

$("#id").keyup(function(){
    if ($(this).val().split('').pop() !== '?') {
        $(this).val($(this).val() + "?");
    }
});

DEMO

EDIT:

(function($) {
  $.fn.setCursorPosition = function(pos) {
    if ($(this).get(0).setSelectionRange) {
      $(this).get(0).setSelectionRange(pos, pos);
    } else if ($(this).get(0).createTextRange) {
      var range = $(this).get(0).createTextRange();
      range.collapse(true);
      range.moveEnd('character', pos);
      range.moveStart('character', pos);
      range.select();
    }
  }
}(jQuery));
$("#id").keyup(function(){
    if ($(this).val().split('').pop() !== '?') {
        $(this).val($(this).val() + "?");
        $(this).setCursorPosition( $(this).val().length - 1)
    }
});

new DEMO

edited Jun 01 '12 at 19:03

answered Jun 01 '12 at 18:55

qwertymk

34,200
28
121
184

@amnotiam So why did you delete it? – qwertymk Jun 01 '12 at 18:58
Your demo shows that a `?` is placed every other letter. At least in Firefox. – Jun 01 '12 at 18:58
@amnotiam that's because the cursor is placed after the `?` so then when you type, the last letter isn't a `?` anymore. – qwertymk Jun 01 '12 at 18:59
I don't think that's the desired outcome. I'm pretty sure OP wants to maintain a question mark at the end as they type. Not sure though. – Jun 01 '12 at 19:00
So then you need a [**cursor setting function also**](http://stackoverflow.com/questions/499126/jquery-set-cursor-position-in-text-area) – qwertymk Jun 01 '12 at 19:01
Yes, am not i am, that's what i was trying to do but failed. – Jun 01 '12 at 19:02
comments on the code would be nice, thanks either way for posting – Jul 19 '15 at 07:39

score 0 · Answer 2 · answered Jun 01 '12 at 19:04

// Input is way better than keyup, although not cross-browser
// but a jquery plugin can add its support.
$('#id').on('input', function() {
    // If the last character isn't a question mark, add it
    if ( this.value[ this.value.length - 1 ] !== '?' ) {
        this.value += '?';
    }
});

JavaScript/jQuery – Add a character at the end of an input field

2 Answers2

DEMO

new DEMO