Javascript cursor position in a textarea or textfield

Essence

To obtain the text cursor position in textarea or in textfield. Cursor position is provided either in characters, or in pixes relative to top left corner of the textarea.

Why

The library can be used for positioning of a completion popup window in a textarea or input text field right near current text cursor. Given that long text is wrapped in the textarea, the task is not very trivial.

How

The library tries to model text wrapping in the textarea and to find out relative cursor position. The results are not 100% accurate, but really close to it. Tested against IE8+, Chrome, Opera, FF.

Usage:

var positioner = new maxkir.CursorPosition(textarea_element, 3); alert(positioner.getCursorCoordinates()); // [x, y] position of cursor in textarea in characters alert(positioner.getPixelCoordinates()); // [x, y] position of cursor in textarea in pixels

See also functional test under test/cursor_position_test.html

Dependencies

None, plain javascript code

-- Copyright (c) 2010-2012 Kirill Maximov, released under the MIT license