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javascript - 当页面被 history.pushState 和 ajax 调用更改时插入内容脚本

转载 作者:搜寻专家 更新时间:2023-11-01 04:15:39 24 4
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我遇到过将内容脚本插入由 history.pushState 和 ajax 调用更改的页面的问题。我找到了 similar topic在 stackoverflow,但该解决方案对我不起作用(该解决方案是使用 chrome.webNavigation.onHistoryStateUpdated 和“popstate”事件)。

这是我的 list 的片段:

"content_scripts": [
{
"matches": ["https://vk.com/audios*", "https://vk.com/al_audio.php*"],
"js": ["jquery-2.1.4.min.js", "getListOfSongs.js"]
}
]

chrome.webNavigation.onHistoryStateUpdated 仅在我导航到另一个页面时有效,如果我按顺序多次导航到同一页面什么都没发生。例如:当

1) 转到 https://vk.com/audios * - 第一次打开页面或重新加载

2) 转到 https://vk.com/some_other_page -ajax调用

3) 转到 https://vk.com/audios * - ajax 调用

1) 转到 https://vk.com/audios * - 第一次打开页面或重新加载

2) 再次转到 https://vk.com/audios * - ajax 调用,此时内容脚本未注入(inject)
3) 再次转到 https://vk.com/audios * - ajax 调用,此时内容脚本未注入(inject)等等

每次我第二次点击同一页面时,都会生成以下请求:

https://vk.com/al_audio.php?__query=audios *********&_ref=left_nav&_smt=audio%3A2&al=-1&al_id=*********&_rndVer=60742

(请求的参数可能会有所不同)

此外,在这种情况下,JQuery .ajaxComplete 不会捕获任何事件。

而且 pushState 不会触发“popstate”事件,所以我不能使用 window.onpopstate 事件

我可能会使用 chrome.webNavigation.onDOMContentLoadedchrome.webNavigation.onCompleted 但是当我重新加载页面时,这些事件会发生不止一次,因此脚本将被注入(inject)不止一次。

这种情况的最佳解决方案是什么?

最佳答案

我能想到的有两种可能的方法:

1 - 使用定时器检查你的脚本是否还在,如果不存在,重新添加...
2 - 检查 ajax 调用,如果它们的 url 与删除脚本的 url 之一匹配,请再次添加脚本。

您的脚本(在 list 中定义的脚本)仍然存在,即使在调用 ajax 之后,它也不会再次运行(不确定历史推送器会发生什么)。所以,我假设您只需要读取一些元素或重新运行 stript。我假设您添加了附加 html 标记的脚本。

所以您需要的是读取元素或重新运行特定代码的东西。


1 - 计时器方法 - 我为希望添加到页面中某个目标元素任何元素(不仅是脚本)创建了一个解决方案。

它使用计时器检查目标元素是否存在。当它找到目标元素时,它会添加我的。然后调整计时器以检查我的元素是否仍然存在。如果没有,请重新添加。

您只需调用一次 appendChildPersistent,它会在您四处导航时一直保持事件状态。

var timers = {}; //stores the setInterval ids

//this is the only method you need to call
//give your script an `id` (1)
//the child is your script, it can be anything JQuery.append can take
//toElem is the Jquery "SELECTOR" of the element to add your script into.
//I'm not sure what would happen if toElem were not a string.
//callback is a function to call after insertion if desired, optional.
appendChildPersistent = function(id, child, toElem, callback)
{
//wait for target element to appear
withLateElement(toElem, function(target)
{
target.append(child); //appends the element - your script
if (typeof callback !== 'undefined') callback(); //execute callback if any

//create a timer to constantly check if your script is still there
timers[id] = setInterval(function()
{
//if your script is not found, clear this timer and tries to add again
if (document.getElementById(id) === null)
{
clearInterval(timers[id]);
delete timers[id];
appendChildPersistent(id, child, toElem, callback);
}
},3000);

});
}

//this function waits for an element to appear on the page
//since you can't foresee when an ajax call will finish
//selector is the jquery selector of the target element
//doAction is what to do when the element is found
function withLateElement(selector, doAction)
{
//checks to see if this element is already being waited for
if (!(selector in timers))
{
//create a timer to check if the target element appeared
timers[selector] = setInterval(function(){
var elem = $(selector);

//checks if the element exists and is not undefined
if (elem.length >= 0)
{
if (typeof elem[0] !== 'undefined')
{
//stops searching for it and executes the action specified
clearInterval(timers[selector]);
delete timers[selector];
doAction(elem);
}
}
}, 2000);
}
}

(1) 脚本标签加个Id好像问题不大:Giving the script tag an ID


2 - 捕获 ajax 调用

一个选项是使用 chrome.webRequest .但奇怪的是,这对我不起作用。下面是另一个选项。

对于这种情况,请检查 this answer ,并且不要忘记阅读那里的Chrome 扩展 的相关答案。只有您遵循整个程序,它才会起作用。幸运的是,我今天测试了它并且效果很好 :p

在这里,您要做的是更改 XMLHttpRequest 方法 opensend 以检测(也可能获取参数)它们何时被调用。

但是,在 Google Extension 中,绝对有必要在页面中注入(inject) stript(不是背景页面或注入(inject)内容脚本的脚本,而是注入(inject)一些代码的内容脚本进入 dom,如下所示)。

var script = document.createElement('script');
script.textContent = actualCode; //actual code is the code you want to inject, the one that replaces the ajax methods
document.head.appendChild(script); //make sure document.head is already loaded before doing it
script.parentNode.removeChild(script); //I'm not sure why the original answer linked removes the script after that, but I kept doing it in my solution

这很重要,因为扩展试图创建一个隔离的环境,而您在此环境中对 XMLHttpRequest 所做的更改将不会参与。 (这就是 JQuery.ajaxComplete 似乎不起作用的原因,您需要在页面中注入(inject)脚本才能使其工作 - look here)

this pure javascript solution ,您替换方法:

//enclosing the function in parentheses to avoid conflict with vars from the page scope
(function() {
var XHR = XMLHttpRequest.prototype;

// Store the orignal methods from the request
var open = XHR.open;
var send = XHR.send;

// Create your own methods to replace those

//this custom open stores the method requested (get or post) and the url of the request
XHR.open = function(method, url) {
this._method = method; //this field was invented here
this._url = url; //this field was invented here
return open.apply(this, arguments); //calls the original method without any change

//what I did here was only to capture the method and the url information
};


//this custom send adds an event listener that fires whenever a request is complete/loaded
XHR.send = function(postData) {
//add event listener that fires when request loads
this.addEventListener('load', function() {
//what you want to do when a request is finished
//check if your element is there and readd it if necessary
//if you know the exact request url, you can put an if here, but it's not necessary

addMyElementsToPage(); //your custom function to add elements
console.log("The method called in this request was: " + this._method);
console.log("The url of this request was: " + this._url);
console.log("The data retrieved is: " + this.responseText);

});

//call the original send method without any change
//so the page can continue it's execution
return send.apply(this, arguments);

//what we did here was to insert an interceptor of the success of a request and let the request continue normally
};
})();

关于javascript - 当页面被 history.pushState 和 ajax 调用更改时插入内容脚本,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31073493/

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