gm4-polyfill-1.0.1

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gm4-polyfill-1.0.1

Polyfill for backward compatibilty of GM functions
此脚本不应直接安装。它是供其他脚本使用的外部库，要使用该库请加入元指令 // @require https://update.greasyfork.icu/scripts/375359/652238/gm4-polyfill-101.js
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/* gm4-polyfill.js v1.0.1 */

// ==UserLibrary==
// @pseudoHeader
// @version     1.0.1
// @name        GM4 PolyFill
// ==/UserLibrary==

/*   This helper script bridges backwardly compatibility between the Greasemonkey 4 APIs and
   existing/legacy APIs.  Say for example your user script includes
   
   // @grant GM_getValue
   
   And you'd like to be compatible with both Greasemonkey 3 and Greasemonkey 4
   (and for that matter all versions of Violentmonkey, Tampermonkey, and any other
   user script engine).  Add:
   
   // @grant GM.getValue
   // @require     https://raw.githubusercontent.com/SloaneFox/code/master/gm4-polyfill.js
   
   Eg, this will define GM.getValue in older GM versions, so updated code will be backward compatible
   to older GM versions.  It will not define GM_getValue in newer GM versions.
   Missing functions from the new GM api are added, hence GM.registerMenuCommand and GM.addStyle are defined.

   Include above and recode userscript to the new (GM-dot) APIs, which return promises.  If your script
   is running in an engine that does not provide the new asynchronous APIs, this
   helper will add them, based on the old APIs.
   
   If you use `await` at the top level, you'll need to wrap your script in an
   `async` function to be compatible with any user script engine besides
   Greasemonkey 4.
   
   var gValue;
   async function init_globals() { gValue = await GM.getValue('x'); }
   async main() { await init_globals(); }
   addEventListener("load",main);

*/
 
if (typeof GM == 'undefined')
	eval("var GM = {};");  // Defined in the closure given when loaded/injected prevents intra-script clobbering.  Eval needed due to GM's declaration as a const in scope wrapper .


if (typeof GM_addStyle == 'undefined') {
	this.GM_addStyle = (aCss) => {
		'use strict';
		let head = document.getElementsByTagName('head')[0];
		if (head) {
			let style = document.createElement('style');
			style.setAttribute('type', 'text/css');
			style.textContent = aCss;
			head.appendChild(style);
			return style;
		}
		return null;
	};
}
GM.addStyle=this.GM_addStyle;

if (typeof GM_getResourceText == 'undefined')
	this.GM_getResourceText = async aResourceName =>
	( await fetch(await GM.getResourceUrl(aResourceName)) ).text(); 

if (typeof GM_registerMenuCommand=="function" && /is not supported[^]{0,100}$/.test(GM_registerMenuCommand.toString()))
	GM_registerMenuCommand=undefined;

GM.registerMenuCommand = function (caption, commandFunc, accessKey) {
	let body=document.body;
	if (!body) throw "GM registerMenuCommand aint got no body in document, call again later.";
	let contextMenu = body.getAttribute('contextmenu');
	let menu = (contextMenu ? document.querySelector('menu#' + contextMenu) : null);
	if (!menu) {
		menu = document.createElement('menu');
		menu.setAttribute('id', 'gm-registered-menu');
		menu.setAttribute('type', 'context');
		body.insertBefore(menu,body.firstChild);
		body.setAttribute('contextmenu', 'gm-registered-menu');
	}
	let menuItem = document.createElement('menuitem');
	menuItem.setAttribute("label",caption);
	menuItem.addEventListener('click', commandFunc, true);
	menu.appendChild(menuItem);
	return menuItem;    // The real GM_registerMenuCommand returns undefined.  Here user can change eg, label attribute of returned menuItem.
};

if (typeof GM_registerMenuCommand == 'undefined') this.GM_registerMenuCommand=GM.registerMenuCommand;

Object.entries({
	'log': console.log.bind(console),
	'info': typeof GM_info == "undefined" ? null : GM_info 
}).forEach(([newKey, old]) => {
	if (old && (typeof GM[newKey] == 'undefined')) {
		GM[newKey] = old;
	}
});

Object.entries({          // Object.entries() returns a 2-d array of all the given object's name value pairs.
	'GM_addStyle': 'addStyle',
	'GM_deleteValue': 'deleteValue',
	'GM_getResourceURL': 'getResourceUrl',
	'GM_getValue': 'getValue',
	'GM_listValues': 'listValues',
	'GM_notification': 'notification',
	'GM_openInTab': 'openInTab',
	'GM_registerMenuCommand': 'registerMenuCommand',
	'GM_setClipboard': 'setClipboard',
	'GM_setValue': 'setValue',
	'GM_xmlhttpRequest': 'xmlHttpRequest',
	'GM_getResourceText': 'getResourceText'
}).forEach(([oldKey, newKey]) => {         // Enables eg, "await GM.getValue" to run ok on pre GM4. But not vice versa, ie, it defines no GM_getValue in newer GM.
	let old = this[oldKey];
	if (old && (typeof GM[newKey] == 'undefined')) {
		GM[newKey] = function(...args) {
			return new Promise(function(resolve, reject) { try {
				resolve(old.apply(this, args));
			} catch (e) { reject(e); }
														 });
		};//GM[newKey]=func
	}
});//forEach()