maple3142 · July 7, 2020 00:58
diff --git a/onbeforescriptexecute.js b/onbeforescriptexecute.js
 // 'beforescriptexecute' event [es5]
 // original version: https://gist.github.com/jspenguin2017/cd568a50128c71e515738413cd09a890

 ;(function() {
 	;('use strict')
 	function Event(script, target) {
 		this.script = script
 		this.target = target

 		this._cancel = false
 		this._replace = null
 		this._stop = false
 	}
 	Event.prototype.preventDefault = function() {
 		this._cancel = true
 	}
 	Event.prototype.stopPropagation = function() {
 		this._stop = true
 	}
 	Event.prototype.replacePayload = function(payload) {
 		this._replace = payload
 	}

 	var callbacks = []
 	var addBeforeScriptExecuteListener = function(f) {
 		if (!f instanceof Function) {
 			throw new Error('Event handler must be a function.')
 		}
 		callbacks.push(f)
 	}
 	var removeBeforeScriptExecuteListener = function(f) {
 		var i = callbacks.length
 		while (i--) {
 			if (callbacks[i] === f) {
 				callbacks.splice(i, 1)
 			}
 		}
 	}
 	var addev = window.addEventListener.bind(window)
 	var rmev = window.removeEventListener.bind(window)
 	window.addEventListener = function() {
 		if (arguments[0].toLowerCase() === 'beforescriptexecute') addBeforeScriptExecuteListener(arguments[1])
 		else addev.apply(null, arguments)
 	}
 	window.removeEventListener = function() {
 		if (arguments[0].toLowerCase() === 'beforescriptexecute') removeBeforeScriptExecuteListener(arguments[1])
 		else rmev.apply(null, arguments)
 	}

 	var dispatch = function(script, target) {
 		var e = new Event(script, target)

 		if (window.onbeforescriptexecute instanceof Function) {
 			try {
 				window.onbeforescriptexecute(e)
 			} catch (err) {
 				console.error(err)
 			}
 		}

 		for (var i = 0; i < callbacks.length; i++) {
 			if (e._stop) {
 				break
 			}
 			try {
 				callbacks[i](e)
 			} catch (err) {
 				console.error(err)
 			}
 		}

 		return e
 	}
 	var observer = new MutationObserver(mutations => {
 		for (var i = 0; i < mutations.length; i++) {
 			for (var j = 0; j < mutations[i].addedNodes.length; j++) {
 				var el = mutations[i].addedNodes[j]
 				if (el.tagName !== 'SCRIPT') continue
 				var e = dispatch(el, mutations[i].target)
 				if (e._cancel) {
 					el.remove()
 				} else if (typeof e._replace === 'string') {
 					el.textContent = e._replace
 				}
 			}
 		}
 	})
 	observer.observe(document, {
 		childList: true,
 		subtree: true
 	})
 })()
diff --git a/onbeforescriptexecute.min.js b/onbeforescriptexecute.min.js
 !function(){function e(e,t){this.script=e,this.target=t,this._cancel=!1,this._replace=null,this._stop=!1}e.prototype.preventDefault=function(){this._cancel=!0},e.prototype.stopPropagation=function(){this._stop=!0},e.prototype.replacePayload=function(e){this._replace=e};var t=[],n=window.addEventListener.bind(window),o=window.removeEventListener.bind(window);window.addEventListener=function(){"beforescriptexecute"===arguments[0].toLowerCase()?function(e){if(!e instanceof Function)throw new Error("Event handler must be a function.");t.push(e)}(arguments[1]):n.apply(null,arguments)},window.removeEventListener=function(){"beforescriptexecute"===arguments[0].toLowerCase()?function(e){for(var n=t.length;n--;)t[n]===e&&t.splice(n,1)}(arguments[1]):o.apply(null,arguments)};var r=function(n,o){var r=new e(n,o);if(window.onbeforescriptexecute instanceof Function)try{window.onbeforescriptexecute(r)}catch(e){console.error(e)}for(var i=0;i<t.length&&!r._stop;i++)try{t[i](r)}catch(e){console.error(e)}return r};new MutationObserver(e=>{for(var t=0;t<e.length;t++)for(var n=0;n<e[t].addedNodes.length;n++){var o=e[t].addedNodes[n];if("SCRIPT"===o.tagName){var i=r(o,e[t].target);i._cancel?o.remove():"string"==typeof i._replace&&(o.textContent=i._replace)}}}).observe(document,{childList:!0,subtree:!0})}();
diff --git a/test.html b/test.html
 <!DOCTYPE html>
 <html lang="en">
 <head>
 	<meta charset="UTF-8">
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
 	<meta http-equiv="X-UA-Compatible" content="ie=edge">
 	<title>Document</title>
 </head>
 <body>
 	<script src="onbeforescriptexecute.js"></script>
 	<script>
 	window.addEventListener('beforescriptexecute',e => {
 		if (e.script.textContent.includes('alert')) {
 			e.preventDefault()
 		}
 		else if (e.script.innerHTML.includes('hello')) {
 			e.replacePayload(e.script.innerHTML.replace(/hello/g, 'world'))
 		}
 		else if (e.script.src.includes('xxx')) {
 			e.preventDefault()
 		}
 	})
 	</script>
 	<script>
 		// won't execute
 		alert('hello')
 	</script>
 	<script>
 		// will execute, but 'hello' will be convert to 'world'
 		console.log('hello')
 	</script>
 	<!-- won't execute -->
 	<script src="xxx.js"></script>
 </body>
 </html>
diff --git a/xxx.js b/xxx.js
 alert('C8763')
	// 'beforescriptexecute' event [es5]
	// original version: https://gist.github.com/jspenguin2017/cd568a50128c71e515738413cd09a890

	;(function() {
	;('use strict')
	function Event(script, target) {
	this.script = script
	this.target = target

	this._cancel = false
	this._replace = null
	this._stop = false
	}
	Event.prototype.preventDefault = function() {
	this._cancel = true
	}
	Event.prototype.stopPropagation = function() {
	this._stop = true
	}
	Event.prototype.replacePayload = function(payload) {
	this._replace = payload
	}

	var callbacks = []
	var addBeforeScriptExecuteListener = function(f) {
	if (!f instanceof Function) {
	throw new Error('Event handler must be a function.')
	}
	callbacks.push(f)
	}
	var removeBeforeScriptExecuteListener = function(f) {
	var i = callbacks.length
	while (i--) {
	if (callbacks[i] === f) {
	callbacks.splice(i, 1)
	}
	}
	}
	var addev = window.addEventListener.bind(window)
	var rmev = window.removeEventListener.bind(window)
	window.addEventListener = function() {
	if (arguments[0].toLowerCase() === 'beforescriptexecute') addBeforeScriptExecuteListener(arguments[1])
	else addev.apply(null, arguments)
	}
	window.removeEventListener = function() {
	if (arguments[0].toLowerCase() === 'beforescriptexecute') removeBeforeScriptExecuteListener(arguments[1])
	else rmev.apply(null, arguments)
	}

	var dispatch = function(script, target) {
	var e = new Event(script, target)

	if (window.onbeforescriptexecute instanceof Function) {
	try {
	window.onbeforescriptexecute(e)
	} catch (err) {
	console.error(err)
	}
	}

	for (var i = 0; i < callbacks.length; i++) {
	if (e._stop) {
	break
	}
	try {
	callbacks[i](e)
	} catch (err) {
	console.error(err)
	}
	}

	return e
	}
	var observer = new MutationObserver(mutations => {
	for (var i = 0; i < mutations.length; i++) {
	for (var j = 0; j < mutations[i].addedNodes.length; j++) {
	var el = mutations[i].addedNodes[j]
	if (el.tagName !== 'SCRIPT') continue
	var e = dispatch(el, mutations[i].target)
	if (e._cancel) {
	el.remove()
	} else if (typeof e._replace === 'string') {
	el.textContent = e._replace
	}
	}
	}
	})
	observer.observe(document, {
	childList: true,
	subtree: true
	})
	})()
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>Document</title>
	</head>
	<body>
	<script src="onbeforescriptexecute.js"></script>
	<script>
	window.addEventListener('beforescriptexecute',e => {
	if (e.script.textContent.includes('alert')) {
	e.preventDefault()
	}
	else if (e.script.innerHTML.includes('hello')) {
	e.replacePayload(e.script.innerHTML.replace(/hello/g, 'world'))
	}
	else if (e.script.src.includes('xxx')) {
	e.preventDefault()
	}
	})
	</script>
	<script>
	// won't execute
	alert('hello')
	</script>
	<script>
	// will execute, but 'hello' will be convert to 'world'
	console.log('hello')
	</script>
	<!-- won't execute -->
	<script src="xxx.js"></script>
	</body>
	</html>