CSS Textarea that expands as you type text [duplicate]

Answer 1

I use the following (with jQuery of course):

$(function () {
    'use strict';
    $("textarea").on('change keyup paste input', function () {
        $(this).attr("rows", Math.max($(this).val().split("\n").length || 1, $(this).attr("rows") || 1));
        $(this).css("width", $(this).css("width"));
    }).trigger('change');
});

Note that it responds to various events, only increases the number of lines (i.e. doesn't decrease), triggers an initial change (e.g. to resize when browsing back to a form with lots of lines)