我正在处理一个用户脚本，我刚刚发现当主页发出 AJAX 请求时脚本没有运行。
有没有办法在主页加载和 AJAX 请求上触发用户脚本？
在 AJAX 请求上触发 Greasemonkey 脚本
IT技术
javascript
ajax
firefox
greasemonkey
2021-02-04 02:40:38
2个回答
在 AJAX 请求上重新运行脚本代码的聪明方法是关注页面的关键部分并检查更改。
例如，假设一个页面包含这样的 HTML：
<div id="userBlather">
<div class="comment"> Comment 1... </div>
<div class="comment"> Comment 2... </div>
...
</div>
并且您希望脚本在每条评论进来时对其进行处理。
现在，您可以拦截所有 AJAX 调用，或侦听（已弃用）或使用DOMSubtreeModifiedMutationObservers，但这些方法可能会变得棘手、挑剔且过于复杂。
在一个wild page上获取ajax化内容的一种更简单、更健壮的方法是使用类似waitForKeyElements下面的函数来轮询它。
例如，此脚本将突出显示包含“beer”的注释，因为它们是 AJAX 输入的：
// ==UserScript==
// @name _Refire on key Ajax changes
// @include http://YOUR_SITE.com/YOUR_PATH/*
// @require http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js
// ==/UserScript==
function highlightGoodComments (jNode) {
//***** YOUR CODE HERE *****
if (/beer/i.test (jNode.text () ) ) {
jNode.css ("background", "yellow");
}
//...
}
waitForKeyElements ("#userBlather div.comment", highlightGoodComments);
/*--- waitForKeyElements(): A utility function, for Greasemonkey scripts,
that detects and handles AJAXed content.
IMPORTANT: This function requires your script to have loaded jQuery.
*/
function waitForKeyElements (
selectorTxt, /* Required: The jQuery selector string that
specifies the desired element(s).
*/
actionFunction, /* Required: The code to run when elements are
found. It is passed a jNode to the matched
element.
*/
bWaitOnce, /* Optional: If false, will continue to scan for
new elements even after the first match is
found.
*/
iframeSelector /* Optional: If set, identifies the iframe to
search.
*/
) {
var targetNodes, btargetsFound;
if (typeof iframeSelector == "undefined")
targetNodes = $(selectorTxt);
else
targetNodes = $(iframeSelector).contents ()
.find (selectorTxt);
if (targetNodes && targetNodes.length > 0) {
btargetsFound = true;
/*--- Found target node(s). Go through each and act if they
are new.
*/
targetNodes.each ( function () {
var jThis = $(this);
var alreadyFound = jThis.data ('alreadyFound') || false;
if (!alreadyFound) {
//--- Call the payload function.
var cancelFound = actionFunction (jThis);
if (cancelFound)
btargetsFound = false;
else
jThis.data ('alreadyFound', true);
}
} );
}
else {
btargetsFound = false;
}
//--- Get the timer-control variable for this selector.
var controlObj = waitForKeyElements.controlObj || {};
var controlKey = selectorTxt.replace (/[^\w]/g, "_");
var timeControl = controlObj [controlKey];
//--- Now set or clear the timer as appropriate.
if (btargetsFound && bWaitOnce && timeControl) {
//--- The only condition where we need to clear the timer.
clearInterval (timeControl);
delete controlObj [controlKey]
}
else {
//--- Set a timer, if needed.
if ( ! timeControl) {
timeControl = setInterval ( function () {
waitForKeyElements ( selectorTxt,
actionFunction,
bWaitOnce,
iframeSelector
);
},
300
);
controlObj [controlKey] = timeControl;
}
}
waitForKeyElements.controlObj = controlObj;
}
更新：
为方便起见，waitForKeyElements()现托管在 GitHub 上。
另一种更简单、更小但不太灵活的方法是使用 JavaScript 时间延迟来等待 AJAX/jQuery 加载和完成。例如，如果以下 HTML 是在首次加载后动态生成的：
<div id="userBlather">
<div class="comment"> Comment 1... </div>
<div class="comment"> Comment 2... </div>
...
</div>
然后像这样的greasemonkey脚本将能够修改它：
// Wait 2 seconds for the jQuery/AJAX to finish and then modify the HTML DOM
window.setTimeout(updateHTML, 2000);
function updateHTML()
{
var comments = document.getElementsByClassName("comment");
for (i = 0; i < comments.length; i++)
{
comments[i].innerHTML = "Modified comment " + i;
}
}
请参阅此处的指南：Javascript 中的睡眠/暂停/等待