A utility function, for Greasemonkey scripts, that detects and handles dynamic content.
此腳本不應該直接安裝，它是一個供其他腳本使用的函式庫。欲使用本函式庫，請在腳本 metadata 寫上： // @require https://update.gf.qytechs.cn/scripts/482702/1299083/Wait%20for%20key%20element.js
// ==UserScript==
// @name Wait for key elements
// @namespace http://tampermonkey.net/
// @version 0.1
// @description A utility function, for Greasemonkey scripts, that detects and handles dynamic content.
// @author https://github.com/cgriebel
// @grant none
// @include *
// ==/UserScript==
/*--- waitForKeyElements():
Usage example:
waitForKeyElements ("div.comments", commentCallbackFunction);
//--- Page-specific function to do what we want when the node is found.
function commentCallbackFunction (jNode) {
jNode.text ("This comment changed by waitForKeyElements().");
}
*/
function waitForKeyElements(
selectorTxt, /* Required: The 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. */
waitOnce, /* 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. */
) {
const dataAttr = 'data-wait-for-elements-found';
var targetNodes, targetsFound;
if (typeof iframeSelector == "undefined") {
var nodes = document.querySelectorAll(selectorTxt);
targetNodes = nodes ? [...nodes] : null;
}
else {
// TODO: CG - test iframes, I currently have no use for this
// targetNodes = $(iframeSelector).contents()
// .find(selectorTxt);
}
if (targetNodes && targetNodes.length > 0) {
targetsFound = true;
/*--- Found target node(s). Go through each and act if they
are new.
*/
targetNodes.forEach((node) => {
if (!node.getAttribute(dataAttr)) {
//--- Call the payload function.
var cancelFound = actionFunction(node);
if (cancelFound) {
targetsFound = false;
}
else {
node.setAttribute(dataAttr, true);
}
}
})
}
else {
targetsFound = 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 (targetsFound && waitOnce && 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,
waitOnce,
iframeSelector
);
},
300
);
controlObj[controlKey] = timeControl;
}
}
waitForKeyElements.controlObj = controlObj;
}