small naive javascript spider for the toolbar

spider.js

javascript: (function() {
    var visited = [];
    var recursiveSpider = function(url) {
        if (visited.indexOf(url) != -1) {
            return;
        }
        visited.push(url);
        console.log(url);
        var xhr = new XMLHttpRequest();
        xhr.open('GET', url, true);
        xhr.onreadystatechange = function() {
            if (xhr.readyState === XMLHttpRequest.DONE) {
                if (xhr.status === 200) {
                    var parser = new DOMParser();
                    var doc = parser.parseFromString(xhr.responseText, 'text/html');
                    var links = doc.getElementsByTagName('a');
                    for (var i = 0; i < links.length; i++) {
                        var href = links[i].getAttribute('href');
                        if (href && href.indexOf('#') != 0) {
                            var absUrl = (new URL(href, url)).href;
                            recursiveSpider(absUrl);
                        }
                    }
                }
            }
        };
        xhr.send();
    };
    recursiveSpider(window.location.href);
})();