Sankaku channel hotkeys

// ==UserScript==
// @id             sankaku-channel-hotkeys
// @name           Sankaku channel hotkeys
// @version        1.0
// @namespace
// @author         Tenno Seremel
// @description
// @include        http://chan.sankakucomplex.com/*
// @run-at         document-start
// ==/UserScript==
(function(){

function on_keypress(e) {
    var target = e.target;
    if (target) {
        var target_name = target.nodeName.toLowerCase();
        if (
            (
                (target_name != "input") && (target_name != "textarea")
            ) || (
                (target_name == "input") && (target.getAttribute("type").toLowerCase() == "submit")
            )
        ) {
            var keys = [
                {key: KeyboardEvent.DOM_VK_1, selector: '#rating > .unit-rating .r1-unit'},
                {key: KeyboardEvent.DOM_VK_2, selector: '#rating > .unit-rating .r2-unit'},
                {key: KeyboardEvent.DOM_VK_3, selector: '#rating > .unit-rating .r3-unit'},
                {key: KeyboardEvent.DOM_VK_4, selector: '#rating > .unit-rating .r4-unit'},
                {key: KeyboardEvent.DOM_VK_5, selector: '#rating > .unit-rating .r5-unit'},
                {key: KeyboardEvent.DOM_VK_9, selector: '#paginator > .pagination > a:first-child'},
                {key: KeyboardEvent.DOM_VK_0, selector: '#paginator > .pagination > a:last-child'}
            ];
            for(var i=0, len=keys.length; i<len; ++i){
                var current = keys[i];
                if((e.which == current.key) && !e.ctrlKey && !e.shiftKey && !e.altKey && !e.metaKey) {
                    e.stopPropagation();
                    e.preventDefault();
                    var link = document.querySelector(current.selector);
                    if ((link !== null) && link.focus) {
                        link.focus();
                        break;
                    }
                }
            }
        }
    }
}

document.addEventListener("keypress", on_keypress, false)

})();