我想停止执行站点中的一行，以便浏览器读取除该行之外的整个页面。或者浏览器可能会简单地跳过该 JavaScript 函数的执行。
或者
有没有办法我可以以某种方式调整javascript，以便javascript中的随机数生成函数不生成随机数，而是生成我想要的数字......
我无权访问托管脚本的网站，因此所有这些都需要在客户端完成。
最佳答案
Firefox 目前支持the beforescriptexecute event (自 Version 4, released on March 22, 2011 起)‡。
随着该事件和 the // @run-at document-start directive 、Firefox 和 Greasemonkey 现在似乎在拦截特定方面做得很好 <script>标签。
这对于 Chrome+Tampermonkey 来说仍然是不可能的。对于除 Firefox+Greasemonkey 之外的任何内容，您将需要使用下面其他答案中所示的技术来编写完整的浏览器扩展。
The checkForBadJavascripts function封装了这一点。例如，假设页面有 <script>像这样的标签:
<script>
alert ("Sorry, Sucka! You've got no money left.");
</script>
您可以使用checkForBadJavascripts像这样:
checkForBadJavascripts ( [
[ false,
/Sorry, Sucka/,
function () {
addJS_Node ('alert ("Hooray, you\'re a millionaire.");');
}
]
] );
获得更好的消息。 (^_^)
有关更多信息，请参阅 checkForBadJavascripts 中的内联文档。
要查看完整脚本的演示，请首先访问this page at jsBin 。您将看到 3 行文本，其中两行是由 JS 添加的。
现在，install this script (View source；也在下面。)并重新访问该页面。您将看到 GM 脚本删除了一个坏标签，并用我们的“好”JS 替换了另一个标签。
<小时/>‡ 请注意，只有 Firefox 支持 beforescriptexecute事件。它已从 HTML5 规范中删除，且未指定等效功能。
完整的GM脚本示例(与GitHub和jsBin相同):
给定这个 HTML:
<body onload="init()">
<script type="text/javascript" src="http://jsbin.com/evilExternalJS/js"></script>
<script type="text/javascript" language="javascript">
function init () {
var newParagraph = document.createElement ('p');
newParagraph.textContent = "I was added by the old, evil init() function!";
document.body.appendChild (newParagraph);
}
</script>
<p>I'm some initial text.</p>
</body>
使用这个 Greasemonkey 脚本:
// ==UserScript==
// @name _Replace evil Javascript
// @include http://jsbin.com/ogudon*
// @run-at document-start
// ==/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);
}
关于javascript - 停止执行 Javascript 函数(客户端)或对其进行调整，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24972416/