Function getElementByXpath

Zhiyoo-Enhanced.user.js:434–443

(xpath, contextNode, doc = document)

        return [].slice.call(contextNode.querySelectorAll(css));
    }
    function getElementByXpath(xpath, contextNode, doc = document) {
        contextNode = contextNode || doc;
        try {
            const result = doc.evaluate(xpath, contextNode, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
            // 应该总是返回一个元素节点
            return result.singleNodeValue && result.singleNodeValue.nodeType === 1 && result.singleNodeValue;
        } catch (err) {
            throw new Error(`Invalid xpath: ${xpath}`);
        }
    }
    function getAllElementsByXpath(xpath, contextNode, doc = document) {
        contextNode = contextNode || doc;
        const result = [];