jquery.limitmaxlength.js

jQuery.fn.limitMaxlength = function(options){

	settings = jQuery.extend({
		attribute: "maxlength",
		onInit: function(){},
		onLimit: function(){},
		onEdit: function(){}
	}, options);
	
	// Event handler to limit the textarea
	var onEdit = function(){
		var textarea = jQuery(this);
		var maxlength = parseInt(textarea.attr('maxlength'));

		if(textarea.val().length > maxlength){
			textarea.val(textarea.val().substr(0, maxlength));
			jQuery.proxy(settings.onLimit, this)();
		}

		jQuery.proxy(settings.onEdit, this)();
	}
	
	this.each(settings.onInit);

	return this.keyup(onEdit)
				.focus(onEdit)
				.focusout(onEdit);
}

limitmaxlength.example.js

$(document).ready(function(){
	
	var onEditCallback = function(){
		var length = $(this).val().length;
		var maxlength = parseInt($(this).attr('maxlength'));			
		
		$(this)
			.siblings('#charsRemaining')
			.text('Characters remaining ' + (maxlength-length));
	}
	
	$('textarea[maxlength]').limitMaxlength({
		onInit: onEditCallback,
		onEdit: onEditCallback,
	});
});

@Silvialenciu You have my permission to copy, use, modify, or redistribute the code in any way without attributing me.