无法获取要点击的链接并使用PhantomJS切换到下一页 [英] Cannot get link to be clicked and switch to next page using PhantomJS

问题描述

我在让phantomJS点击网站上的登录按钮时遇到问题。

I am having an issue getting phantomJS to click the login button on a website.

我可以在我的第二个屏幕截图中看到它正在尝试选择登录按钮，但我无法等待并在下一页上截取屏幕截图。

I can see in my second screenshot that it is trying to select the login button, but I cannot get it to wait and take the screenshot on the next page.

这是我的JS文件：

var page = require('webpage').create();
page.viewportSize = {width: 1920,height: 1080};
page.open('http://clubs.bluesombrero.com/default.aspx?portalid=1809', function (status) {
    console.log("Status: " + status);
    if (status === "success") {
        var url = page.url;
        console.log('URL: ' + url);
        console.log("TC0001: Pass");
        page.render('TC0001.png');

        var a = page.evaluate(function() {
        return document.querySelector('#dnn_dnnLOGIN_cmdLogin');
        });

        page.sendEvent('click', a.offsetLeft, a.offsetTop);

        page.render('TC0002.png');
    } else {
        console.log("TC0001: Failed, Page did not load.");
    }
    phantom.exit();
});

我已尝试了一些方法让它等到页面加载后截取屏幕截图，但我没有运气。

I have tried a few ways to get it to wait to take the screenshot after the page has loaded, but I have not had any luck.

推荐答案

page.sendEvent（）是一个完成的同步函数它的行动一旦完成。即使在点击触发的请求被应答之前，也会执行下一个调用（ page.render（））。

page.sendEvent() is a synchronous function that finishes as soon as its action is done. The next call (page.render()) is executed even before the request which was triggered by the click is answered.

JavaScript提供了两个等待静态时间的函数： setTimeout 和 setInterval ：

JavaScript provides two functions to wait a static amount of time: setTimeout and setInterval:

page.sendEvent('click', a.offsetLeft, a.offsetTop);

setTimeout(function(){
    page.render('TC0002.png');
    phantom.exit();
}, 5000);

（别忘了删除其他 phantom.exit（）因为你不想太早退出）

(don't forget to remove the other phantom.exit() since you don't want to exit too early)

当然现在的问题是，一方面页面仍然可能没有准备就绪5秒或另一方面，页面加载非常快，只是坐在那里什么都不做。

Of course the problem is now that on one hand the page still might not be ready after 5 seconds or on the other hand the page was loaded extremely fast and just sits there doing nothing.

更好的方法是使用 waitFor（） function 在examples文件夹中提供PhantomJS。您可以等待特定元素的特定条件：

A better approach would be to use the waitFor() function that is provided in the examples folder of PhantomJS. You can wait for a specific condition of the page like the existence of a specific element:

page.sendEvent('click', a.offsetLeft, a.offsetTop);

waitFor(function _testFx(){
    return page.evaluate(function(){
        return !!document.querySelector("#someID");
    });
}, function _done(){
    page.render('TC0002.png');
    phantom.exit();
}, 10000);

3。 page.onLoadFinished

另一种方法是收听 page.onLoadFinished 将在下一页加载时调用的事件，但您应该在点击之前注册：

3. page.onLoadFinished

Another approach would be to listen to the page.onLoadFinished event which will be called when the next page is loaded, but you should register to it before you click:

page.onLoadFinished = function(){
    page.render('TC0002.png');
    phantom.exit();
};

page.sendEvent('click', a.offsetLeft, a.offsetTop);

4。 page.onPageCreated

每当在桌面浏览器中打开新窗口/标签时， page.onPageCreated 将在PhantomJS中触发。它提供了对新创建页面的引用，因为前一页面没有被覆盖。

4. page.onPageCreated

Whenever a new window/tab would be opened in a desktop browser, the page.onPageCreated would be triggered in PhantomJS. It provides a reference to the newly created page, because the previous page is not overwritten.

page.onPageCreated = function(newPage){
    newPage.render('TC0002.png');
    newPage.close();

    phantom.exit();
};

page.sendEvent('click', a.offsetLeft, a.offsetTop);

在所有其他情况下，页面实例被新页面覆盖。

In all the other cases, the page instance is overwritten by the new page.

这可能仍然不够，因为PhantomJS没有指定加载页面时的含义以及页面的JavaScript仍然可能进一步要求建立页面。这个Q& A提供了一些等待完整页面加载的好建议： phantomjs不等待完整页面加载

That might still not be sufficient, because PhantomJS doesn't specify what it means when a page is loaded and the JavaScript of the page may still make further requests to build up the page. This Q&A has some good suggestions to wait for a "full" page load: phantomjs not waiting for "full" page load

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