jquery.autogrow.js

/* 
 * Auto Expanding Text Area (1.2.2)
 * by Chrys Bader (www.chrysbader.com)
 * chrysb@gmail.com
 *
 * Version 1.2.3 update
 * by Richard Vallee
 * richardvallee@gmail.com
 *
 * Special thanks to:
 * Jake Chapa - jake@hybridstudio.com
 * John Resig - jeresig@gmail.com
 *
 * Copyright (c) 2008 Chrys Bader (www.chrysbader.com)
 * Licensed under the GPL (GPL-LICENSE.txt) license. 
 *
 *
 * NOTE: This script requires jQuery to work.  Download jQuery at www.jquery.com
 *
 */
 
(function(jQuery) {
		  
	var self = null;
 
	jQuery.fn.autogrow = function(o)
	{	
		return this.each(function() {
			new jQuery.autogrow(this, o);
		});
	};
	

    /**
     * The autogrow object.
     *
     * @constructor
     * @name jQuery.autogrow
     * @param Object e The textarea to create the autogrow for.
     * @param Hash o A set of key/value pairs to set as configuration properties.
     * @cat Plugins/autogrow
     */
	
	jQuery.autogrow = function (e, o)
	{
		this.options		  	= o || {};
		this.dummy			  	= null;
		this.interval	 	  	= null;
		this.line_height	  	= this.options.lineHeight || parseInt(jQuery(e).css('line-height'));
		this.min_height		  	= this.options.minHeight || parseInt(jQuery(e).css('min-height'));
		this.max_height		  	= this.options.maxHeight || parseInt(jQuery(e).css('max-height'));;
		this.textarea		  	= jQuery(e);
		this.expand_tolerance	= (!isNaN(this.options.expandTolerance) && this.options.expandTolerance > 0) ? this.options.expandTolerance : 4;
		
		if(isNaN(this.line_height))
		  this.line_height = 0;
		
		// Only one textarea activated at a time, the one being used
		this.init();
	};
	
	jQuery.autogrow.fn = jQuery.autogrow.prototype = {
    	autogrow: '1.2.3'
  	};
	
 	jQuery.autogrow.fn.extend = jQuery.autogrow.extend = jQuery.extend;
	
	jQuery.autogrow.fn.extend({
		init: function() {			
			var self = this;			
			this.textarea.css({overflow: 'hidden', display: 'block'});
			this.textarea.bind('focus', function() { self.startExpand() } ).bind('blur', function() { self.stopExpand() });
			this.checkExpand();	
		},
						 
		startExpand: function() {				
		  var self = this;
			this.interval = window.setInterval(function() {self.checkExpand()}, 400);
		},
		
		stopExpand: function() {
			clearInterval(this.interval);	
		},
		
		checkExpand: function() {
			if (this.dummy == null) {
				this.dummy = jQuery('<div></div>');
				this.dummy.css({
					'font-size'  : this.textarea.css('font-size'),
					'font-family': this.textarea.css('font-family'),
					'width'      : this.textarea.css('width'),
					'padding'    : this.textarea.css('padding'),
					'line-height': this.line_height + 'px',
					'overflow-x' : 'hidden',
					'position'   : 'absolute',
					'top'        : 0,
					'left'		 : -9999
					}).appendTo('body');
			} else {
				// If the dummy was already created, show it as it is hidden after expansion
				this.dummy.show();
			}
			
			// Strip HTML tags
			var html = this.textarea.val().replace(/(<|>)/g, '');
			
			// IE is different, as per usual
			if (jQuery.browser.msie) {
				html = html.replace(/\n/g, '<BR/>new');
			}
			else {
				html = html.replace(/\n/g, '<br/>new');
			}
			
			if (this.dummy.html() != html) {
				this.dummy.html(html);	
				if (this.max_height > 0 && (this.dummy.height() + (this.expand_tolerance*this.line_height) > this.max_height)) {
					this.textarea.css('overflow-y', 'auto');
					if (this.textarea.height() < this.max_height) {
						this.textarea.animate({height: (this.max_height + (this.expand_tolerance*this.line_height)) + 'px'}, 100);	
					}
				}
				else {
					this.textarea.css('overflow-y', 'hidden');
					if (this.textarea.height() < this.dummy.height() + (this.expand_tolerance*this.line_height) || (this.dummy.height() < this.textarea.height())) {	
						if (this.dummy.height() < this.min_height) {
							this.textarea.animate({height: (this.min_height + (this.expand_tolerance*this.line_height)) + 'px'}, 100);	
						} else {
							this.textarea.animate({height: (this.dummy.height() + (this.expand_tolerance*this.line_height)) + 'px'}, 100);	
						}
					}
				}
			}

			// Hide the dummy, as otherwise it overflows the body when the content is long
			this.dummy.hide();
		}
						 
	 });
})(jQuery);