Hello

，我有xpath = /html[1]/body[1]/div[1]这个元素

我想获得字符串 “Hello”

我知道有一个函数在JavaScript中检索元素：

var xPathResult = document.evaluate(xPath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null);，

但我几乎总是检索null。 所有的代码在这里：

chrome.runtime.onConnectExternal.addListener(function (port) {

port.onMessage.addListener(function (msg) {

var index;

if (msg != null) {

// console.log("Received message: " + msg);

var objJSON = JSON.parse(msg);

for (index = 0; index < objJSON.length; ++index) {

var xpath = objJSON[index].xpath;

var url = objJSON[index].url;

if (xpath != "Not looking at browser") {

var xp = getElementByXPath(xpath); //returns null all the time

var value = xp.innerHTML;

}

}

}

});

});

var getElementByXPath = function (xPath) {

var xPathResult = document.evaluate(xPath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null);

return xPathResult.singleNodeValue;

};

你能帮忙吗？在xpaths中没有错误 - 在运行时没有错误的xpath抛出异常，如果我通过xpaths检查Chrome中的元素，它也看起来没问题。