Create tooltip at cursor position in text area with jQuery

I'm trying to create a tooltip above the input caret in a text area. This would be easy if I could get the x,y coordinates of the caret in the text area, however I've been searching for a little while and cannot figure out how to do that.

开发者_开发问答Say a user is typing in a text area and then presses some key (@ symbol for instance). I'm trying to show a little tooltip above the text area caret.

Any ideas?

Hmmm I do not really see anything in jQuery events that will easily give you an x y coord for the caret.

However there are quite a few ways for detecting the caret position in a text field:

http://laboratorium.0xab.cd/jquery/fieldselection/0.1.0/test.html

Is it possible to programmatically detect the caret position within a <input type=text> element?

Caret position in textarea, in characters from the start

Using this, you could try to estimate the pixel coordinates for the tool tip.

If you want it to be more exact use a monospaced font inside of your text fields.

//depending on size of font
var charWidth = 10;
//using any number of the above methods to get caret position
var caretPosition = getCaretPos('#myTextField');
var textFieldOffsetX = $('#myTextField').offset.left;
var toopTipPositionX = caretPosition * charWidth + textFieldOffsetX;

It is not exact and it is not going to be perfect, but it might be close enough.

Why does the tooltip have to be at the caret? Why not position it above (or somewhere around) the textarea? Here is a demo of what I mean.

$('textarea').keyup(function(e) {
    switch (e.which) {
        // @ symbol
    case 50:
        makeTooltip(e, 'you typed in an at symbol');
        break;
    }
});