// ============================================================

var key_right = 39;
var key_left = 37;
var key_return = 13;

// ============================================================

function navigate(key) {
    var next;
    var prev;
    $("html head link").each(function(){
	if (this.rel == "next") {
	    next = this.href;
	}
	if (this.rel == "prev") {
	    prev = this.href;
	}
    });

    if ((key == key_right || key == key_return) && next != undefined) {
	window.location = next
    } else if (key == key_left && prev != undefined) {
	window.location = prev;
    }
}

// ============================================================

$(document).ready(function(){
    $(document).keypress(function(e) {
	navigate(e.keyCode);
    });
});