Find value of current line of a <textarea> using javascript

Question

How can I find the value of the current line of a textarea?

I know I have to find the caret position, but then find everything before it up to the last \\n and every

Answer 1

In line with nickf's answer, the following example (which uses jQuery) may be a bit faster because it uses (lastI|i)ndexOf:

function current_line(textarea) {
  var $ta = $(textarea),
      pos = $ta.getSelection().start, // fieldselection jQuery plugin
      taval = $ta.val(),
      start = taval.lastIndexOf('\n', pos - 1) + 1,
      end = taval.indexOf('\n', pos);

  if (end == -1) {
      end = taval.length;
  }

  return taval.substr(start, end - start);
}

Here it is on jFiddle.