isElementInDocument.js

//http://d.hatena.ne.jp/amachang/20100624/1277359266
var isElementInDocument = (function() {
    function isElementInDocumentA(node) {
        return node != null && (node.nodeType == 9 || (node.compareDocumentPosition(node.ownerDocument) & 1) == 0);
    }
    function isElementInDocumentB(node) {
        return node != null && (node.nodeType == 9 || node.ownerDocument.documentElement === node || node.ownerDocument.documentElement.contains(node));
    }
    function isElementInDocumentC(node) {
        var target = node;
        while(target) {
            if (target.nodeType == 9) return true;
            target = target.parentNode;
        }
        return false;
    }
    return document.compareDocumentPosition  ? isElementInDocumentA :
           document.documentElement.contains ? isElementInDocumentB :
                                               isElementInDocumentC ;
})();