JQuery

Facebook Style Expanding textareas

I found this plugin just now that works great at making Facebook style self expanding textareas:

Self expanding textareas

There is, however, one error in it. When you first download and use the extension you will realise that when the textarea is empty it shrinks below its defined height. I decided to look into this and it was as simple as the function not being implemented correctly so I added this line:

					if (scrollTop < $(this).height()) { toChange.height($(this).height()); return; }

Basically I check to see if the textarea will be changed to smaller than the predefined height and if it will be then I redefine textarea height to its original height and exit from the function to stop any further processing making the amended plugin:

/*
 * jQuery autoResize (textarea auto-resizer)
 * @copyright James Padolsey http://james.padolsey.com
 * @version 1.04
 */

(function($){
    
    $.fn.autoResize = function(options) {
        
        // Just some abstracted details,
        // to make plugin users happy:
        var settings = $.extend({
            onResize : function(){},
            animate : true,
            animateDuration : 150,
            animateCallback : function(){},
            extraSpace : 20,
            limit: 1000
        }, options);
        
        // Only textarea's auto-resize:
        this.filter('textarea').each(function(){
            
                // Get rid of scrollbars and disable WebKit resizing:
            var textarea = $(this).css({resize:'none','overflow-y':'hidden'}),
                // Cache original height, for use later:
            	origHeight = $(this).height(),
                
                // Need clone of textarea, hidden off screen:
                clone = (function(){
                    
                    // Properties which may effect space taken up by chracters:
                    var props = ['height','width','lineHeight','textDecoration','letterSpacing'],
                        propOb = {};
                        
                    // Create object of styles to apply:
                    $.each(props, function(i, prop){
                        propOb[prop] = textarea.css(prop);
                    });
                    
                    // Clone the actual textarea removing unique properties
                    // and insert before original textarea:
                    return textarea.clone().removeAttr('id').removeAttr('name').css({
                        position: 'absolute',
                        top: 0,
                        left: -9999
                    }).css(propOb).attr('tabIndex','-1').insertBefore(textarea);
					
                })(),
                lastScrollTop = null,
                updateSize = function() {
					
                    // Prepare the clone:
                    clone.height(0).val($(this).val()).scrollTop(10000);
					
                    // Find the height of text:
                    var scrollTop = Math.max(clone.scrollTop(), origHeight) + settings.extraSpace,
                        toChange = $(this).add(clone);
						
                    // Don't do anything if scrollTip hasen't changed:
                    if (lastScrollTop === scrollTop) { return; }
					if (scrollTop < $(this).height()) { toChange.height($(this).height()); return; }
                    lastScrollTop = scrollTop;
					
                    // Check for limit:
                    if ( scrollTop >= settings.limit ) {
                        $(this).css('overflow-y','');
                        return;
                    }
                    // Fire off callback:
                    settings.onResize.call(this);
					
                    // Either animate or directly apply height:
                    settings.animate && textarea.css('display') === 'block' ?
                        toChange.stop().animate({height:scrollTop}, settings.animateDuration, settings.animateCallback)
                        : toChange.height(scrollTop);
                };
            
            // Bind namespaced handlers to appropriate events:
            textarea
                .unbind('.dynSiz')
                .bind('keyup.dynSiz', updateSize)
                .bind('keydown.dynSiz', updateSize)
                .bind('change.dynSiz', updateSize);
            
        });
        
        // Chain:
        return this;
        
    };
    
    
    
})(jQuery);

This now works as shown in the demo on the programmers page for this plugin.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s