XPath to find elements that does not have an id or class

Question

How can I get all tr elements without id attribute?

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Than

Answer 1

if (elm.hasAttribute('id')) { 
//if id - implement here
    } else if (elm.hasAttribute('class')) { 
        //if class - implement here
    } else { 
        for (i = 1, sib = elm.previousSibling; sib; sib = sib.previousSibling) { 
            if (sib.localName == elm.localName)
                i++;
        }; 
        segs.unshift(elm.localName.toLowerCase() + '[' + i + ']'); 
    }