Find position of cursor in textarea

Why isn't this code working?

http://sandbox.phpcode.eu/g/5db40.php

<form>
   <textarea></textarea>
</form>
<script>
$(function(){
    $("textarea").keydown(function(e){
        if (e.keyCode == 9)开发者_StackOverflow中文版{

                     $("textarea").selectionStart.append("    ");
                     e.preventDefault();
        }
    });
});
</script>

You have to press TAB on textarea

Problem is that it doesn't do/append four spaces and it does default browser action (switch to adress tab in Chrome)

Thoughts?

Related to this question, try:

$(function () {
    $("textarea").keydown(function (e) {
        if (e.keyCode == 9) {
            e.preventDefault();
            var $this = $(this);
            var pos = $this[0].selectionStart;
            $this.val($this.val().substring(0, pos) + "    " + $this.val().substring(pos));
            $this.setCursorPosition(pos + 4);
        }
    });
});

And add the JQuery from this post.

new 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);

For manipulating textarea selections and caret positions in jQuery, I recommend using my jQuery plug-in for doing this, which work in all major browsers and provides methods for getting and setting the caret/selection position, inserting content at the caret position and more. The code you want would be:

$("textarea").keydown(function(e) {
    if (e.keyCode == 9) {
        e.preventDefault();
        $(this).replaceSelectedText("    ");
    }
});

Take a look at Keypress in jQuery: Press TAB inside TEXTAREA (when editing an existing text)

Try this one, i'm damn sure it will work.

<form> 
   <textarea></textarea> 
</form> 
<script> 
$(function(){ 
    $("textarea").keydown(function(e){ 
        if (e.which == 9){ 

                     $("textarea").append("    "); 
                     return false;
        } 
    }); 
}); 
</script>

I just simply changed the word "keyCode" to "which", 'cause the word keyCode is derived from jquery ui.

var range = $(this).get(0).createTextRange();
range.collapse(true);
range.moveEnd('character', pos);
range.moveStart('character', pos);
range.select();

This (JSFiddle) was the best I could manage, but I can't get it working on Firefox or Chrome. If somebody manages to get the button press select text in textarea with Chrome working, feel free to let me know.