javascript 我可以拦截直接调用的函数吗？
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Can I intercept a function called directly?
提问by yilmazhuseyin
In this code I created a function called someFunction. Then I modified Function.prototype.apply and call methods. So instead of my function code is working I am running my interception code (which shows an alert). But neither "call" nor "apply" intercepts direct method call. Is it possiple to intercept this?
在这段代码中，我创建了一个名为 someFunction 的函数。然后我修改了 Function.prototype.apply 并调用了方法。因此，我正在运行我的拦截代码（显示警报），而不是我的函数代码正在运行。但是“调用”和“应用”都不会拦截直接的方法调用。有没有可能拦截这个？
Function.prototype.call = function(){alert("call");};
Function.prototype.apply = function(){alert("apply");};
function someFunction(){}
window.onload = function(){
someFunction.call(this); //call alert is shown
someFunction.apply(this); //apply alert is shown
someFunction(); //how can I intercept this?
}
回答by Andy E
You can only override a known function by setting another function in its place (e.g., you can't intercept ALL function calls):
您只能通过在其位置设置另一个函数来覆盖已知函数（例如，您不能拦截所有函数调用）：
(function () {
// An anonymous function wrapper helps you keep oldSomeFunction private
var oldSomeFunction = someFunction;
someFunction = function () {
alert("intercepted!");
oldSomeFunction();
}
})();
Note that, if someFunctionwas already aliased/referenced by another script before it was changed by this code, those references would still point to the original function not be overridden by the replacement function.
请注意，如果someFunction在此代码更改之前已被另一个脚本别名/引用，则这些引用仍将指向原始函数，不会被替换函数覆盖。
回答by Thomas Eding
Function.prototype.callWithIntercept = function () {
alert("intercept");
return this.apply(null, arguments);
};
var num = parseInt.callWithIntercept("100px", 10);
It is worth noting that in newer versions of JS, there are Proxyobjects you can use:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
值得注意的是，在较新版本的 JS 中，Proxy您可以使用一些对象：https:
//developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
回答by Neal Xiong
There is a chance you can intercept direct function call. This requires:
您有机会拦截直接函数调用。这需要：
- Either the function is created by Function.prototype.bind and you have to overwrite Function.prototype.bind before creating the function, or
- The function is created from Function() (or new Function()) and you also have to overwrite Function function before creating the target function.
- 要么函数是由 Function.prototype.bind 创建的，你必须在创建函数之前覆盖 Function.prototype.bind，或者
- 该函数是从 Function() （或 new Function()）创建的，您还必须在创建目标函数之前覆盖 Function 函数。
If neither of the above two can be met, the only way to intercept a direct call is to wrap the target function, which is the solution provided by AndyE https://stackoverflow.com/a/3406523/1316480
如果以上两个都不能满足，那么拦截直接调用的唯一方法就是包裹目标函数，这是AndyE提供的解决方案https://stackoverflow.com/a/3406523/1316480
For a function that is created by function literal and is hidden in private scope, there is no way to intercept a direct call to it.
对于由函数字面量创建并隐藏在私有作用域中的函数，无法拦截对其的直接调用。
I have a blog post concludes all of these: http://nealxyc.wordpress.com/2013/11/25/intercepting-javascript-function/
我有一篇博文总结了所有这些：http: //nealxyc.wordpress.com/2013/11/25/intercepting-javascript-function/
回答by jhurshman
You could iterate over the global scope and replace any objects of function type you find which aren't "yours".
您可以遍历全局范围并替换您找到的不是“您的”的任何函数类型的对象。
