jquery.simpleautogrow.js

/*
 * Simple Auto Expanding Text Area (0.1.2-dev)
 * by Antti Kaihola (antti.kaihola.fi)
 * akaihol+jquery@ambitone.com
 *
 * Copyright (c) 2009 Antti Kaihola (antti.kaihola.fi)
 * Licensed under the MIT and BSD licenses.
 *
 * NOTE: This script requires jQuery to work.  Download jQuery at
 *       www.jquery.com
 */

(function(jQuery) {

	jQuery.fn.simpleautogrow = function(margin) {
		return this.each(function() { new jQuery.simpleautogrow(this, margin); }); };

	jQuery.simpleautogrow = function (e, margin) {
		var self = this;
		var $e = this.textarea = jQuery(e)
			.css({overflow: 'hidden', display: 'block'})
			.bind('focus', function() {
				this.timer = window.setInterval(function() {self.checkExpand(); }, 200); })
			.bind('blur', function() { clearInterval(this.timer); });
		this.border = $e.outerHeight() - $e.innerHeight();
		try { margin = typeof margin == 'undefined' ? 0 : parseInt(margin); } catch(ex) { margin = 0; }
		this.margin = margin;
		this.clone = $e.clone().css({position: 'absolute', visibility: 'hidden'})
			.attr('name', '').attr('id', '');
		$e.height(e.scrollHeight + this.border)
			.after(this.clone);
		this.checkExpand();
	};

	jQuery.simpleautogrow.prototype.checkExpand = function() {
		var target_height = this.clone[0].scrollHeight + this.border + this.margin;
		if (this.textarea.outerHeight() != target_height)
			this.textarea.height(target_height + 'px');
		this.clone.attr('value', this.textarea.attr('value')).height(0);
	};

})(jQuery);