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var inputs = document.getElementsByTagName("input"),
    size = inputs.length;
Array.prototype.forEach.call(inputs, function(a){
    if (a.type == "text"){
        a.addEventListener("keypress", function(e){
            if (e.keyCode == 13)
                if (this.nextElementSibling == inputs[size])
                    inputs[0].focus();
                else
                    this.nextElementSibling.focus();
        }, false);
    }
});

Input 1: <input type = "text" autofocus />
Input 2: <input type = "text" />
Input 3: <input type = "text" />
Input 4: <input type = "text" />
Input 5: <input type = "text" />

input{
    display: block;
}