Is there a way to get element by XPath using JavaScript in Selenium WebDriver?

I am looking for something like:

getElementByXpath(//html[1]/body[1]/div[1]).innerHTML

I need to get the innerHTML of elements using JS (to use that in Selenium WebDriver/Java, since WebDriver can't find it itself), but how?

I could use ID attribute, but not all elements have ID attribute.

You can use document.evaluate:

Evaluates an XPath expression string and returns a result of the specified type if possible.

It is w3-standardized and whole documented: https://developer.mozilla.org/en-US/docs/Web/API/Document.evaluate

function getElementByXpath(path) {
  return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}

console.log( getElementByXpath("//html[1]/body[1]/div[1]") );

<div>foo</div>

https://gist.github.com/yckart/6351935

There's also a great introduction on mozilla developer network: https://developer.mozilla.org/en-US/docs/Introduction_to_using_XPath_in_JavaScript#document.evaluate

Alternative version, using XPathEvaluator:

function getElementByXPath(xpath) {
  return new XPathEvaluator()
    .createExpression(xpath)
    .evaluate(document, XPathResult.FIRST_ORDERED_NODE_TYPE)
    .singleNodeValue
}

console.log( getElementByXPath("//html[1]/body[1]/div[1]") );

<div>foo/bar</div>