Simple tab emulator, find fields from selector and allows to skip between then.

jquery-tab-emulator.js

var tab = function()
{
	this.fields  = $('input:not(:disabled):not([type="hidden"]):not([readonly="readonly"]), a, select:not(:disabled)');
	this.current = 0;
}

$.extend(tab.prototype, {
	forward: function() {
		this.current++;
		if(this.current > this.fields.length) {
			this.current = 0;
		}
		
		return this.current;
	},
	
	back: function() {
		this.current--;
		if(this.current < 0) {
			this.current = this.fields.length;
		}
	
		return this.current;
	},
	
	focus: function() {
		this.fields[this.current].focus();
	}
});