pal*_*m3D 4 javascript greasemonkey
我正在使用我无法控制的HTML页面.它在内联<script>标记中定义了一个Javascript函数,并将其调用<body onload="...">:
<html>
...
<body onload="init()">
<script type="text/javascript" language="javascript">
function init() {
...
}
</script>
...
如何在调用之前更改该功能？我曾尝试使用Greasemonkey修改脚本或在其后插入另一个脚本来覆盖该函数,但它似乎没有任何效果.
Bro*_*ams 10
Greasemonkey的,现在通常通过利用做这种事情的beforescriptexecute事件和@run-at document-start.请注意,只有Firefox似乎支持该事件,因此这不适用于Chrome.在这里和这里看到更繁琐的方法.
要在init()调用之前更改该函数,请使用checkForBadJavascripts()下面定义的函数.
你会这样称呼它:
//--- New "init" function to replace the bad one.
function init () {
//... Do what you want here...
}
checkForBadJavascripts ( [
[false, /function\s+init(/, function () {addJS_Node (init);} ]
] );
凡function\s+init(必须是唯一的<script>,你的目标标签.(注意,addJS_Node()下面也定义了.)
例如,访问jsBin页面.您将看到3行文本,其中两行由JS添加.
现在,安装以下脚本并重新访问该页面.您将看到GM脚本删除了一个坏<script>标签,并用我们的"好"JS替换了另一个.
// ==UserScript==
// @name _Replace evil Javascript
// @include http://output.jsbin.com/tezoni*
// @run-at document-start
// @grant none
// ==/UserScript==
/****** New "init" function that we will use
instead of the old, bad "init" function.
*/
function init () {
var newParagraph = document.createElement ('p');
newParagraph.textContent = "I was added by the new, good init() function!";
document.body.appendChild (newParagraph);
}
/*--- Check for bad scripts to intercept and specify any actions to take.
*/
checkForBadJavascripts ( [
[false, /old, evil init()/, function () {addJS_Node (init);} ],
[true, /evilExternalJS/i, null ]
] );
function checkForBadJavascripts (controlArray) {
/*--- Note that this is a self-initializing function. The controlArray
parameter is only active for the FIRST call. After that, it is an
event listener.
The control array row is defines like so:
[bSearchSrcAttr, identifyingRegex, callbackFunction]
Where:
bSearchSrcAttr True to search the SRC attribute of a script tag
false to search the TEXT content of a script tag.
identifyingRegex A valid regular expression that should be unique
to that particular script tag.
callbackFunction An optional function to execute when the script is
found. Use null if not needed.
*/
if ( ! controlArray.length) return null;
checkForBadJavascripts = function (zEvent) {
for (var J = controlArray.length - 1; J >= 0; --J) {
var bSearchSrcAttr = controlArray[J][0];
var identifyingRegex = controlArray[J][1];
if (bSearchSrcAttr) {
if (identifyingRegex.test (zEvent.target.src) ) {
stopBadJavascript (J);
return false;
}
}
else {
if (identifyingRegex.test (zEvent.target.textContent) ) {
stopBadJavascript (J);
return false;
}
}
}
function stopBadJavascript (controlIndex) {
zEvent.stopPropagation ();
zEvent.preventDefault ();
var callbackFunction = controlArray[J][2];
if (typeof callbackFunction == "function")
callbackFunction ();
//--- Remove the node just to clear clutter from Firebug inspection.
zEvent.target.parentNode.removeChild (zEvent.target);
//--- Script is intercepted, remove it from the list.
controlArray.splice (J, 1);
if ( ! controlArray.length) {
//--- All done, remove the listener.
window.removeEventListener (
'beforescriptexecute', checkForBadJavascripts, true
);
}
}
}
/*--- Use the "beforescriptexecute" event to monitor scipts as they are loaded.
See https://developer.mozilla.org/en/DOM/element.onbeforescriptexecute
Note that it does not work on acripts that are dynamically created.
*/
window.addEventListener ('beforescriptexecute', checkForBadJavascripts, true);
return checkForBadJavascripts;
}
function addJS_Node (text, s_URL, funcToRun) {
var D = document;
var scriptNode = D.createElement ('script');
scriptNode.type = "text/javascript";
if (text) scriptNode.textContent = text;
if (s_URL) scriptNode.src = s_URL;
if (funcToRun) scriptNode.textContent = '(' + funcToRun.toString() + ')()';
var targ = D.getElementsByTagName ('head')[0] || D.body || D.documentElement;
//--- Don't error check here. if DOM not available, should throw error.
targ.appendChild (scriptNode);
}