函数代理 .toString() 错误 [英] Function Proxy .toString() Errors

问题描述

我正在尝试在函数代理上调用 .toString().

I am trying to call .toString() on a function proxy.

简单地创建函数代理并调用toString导致TypeError: Function.prototype.toString is not generic"，设置toString返回源导致RangeError: Maximum call stack size exceeded"，但是创建了一个gettoString 的陷阱有效.

Simply creating a function proxy and calling toString causes "TypeError: Function.prototype.toString is not generic", setting the toString to return the source of the original causes "RangeError: Maximum call stack size exceeded", but creating a get trap for toString works.

为什么简单地设置 toString 函数不起作用，但设置一个 get 陷阱却起作用?

Why does simply setting the toString function not work, but making a get trap does?

function wrap(source) {
 return(new Proxy(source, {}))
}
wrap(function() { }).toString()

function wrap(source) {
 let proxy = new Proxy(source, {})
 proxy.toString = function() {
  return(source.toString())
 }
 return(proxy)
}
wrap(function() { }).toString()

function wrap(source) {
 return(new Proxy(source, {
  get(target, key) {
   if(key == "toString") {
    return(function() {
     return(source.toString())
    })
   } else {
    return(Reflect.get(source, key))
} } })) }
wrap(function() { }).toString()

推荐答案

我遇到了同样的问题.我终于发现这是this 的问题.将 get 陷阱添加到您的处理程序，如果它是 function，则在代理属性上将代理对象绑定为 this，并且它似乎可以正常工作:

I was having the same issue. I finally figured out that it's an issue with this. Add a get trap to your handler, bind the proxied object as this on the proxied property if it's a function, and it seems to work okay:

function wrap(source) {
    return new Proxy(source, {
        get: function (target, name) {
            const property = target[name];
            return (typeof property === 'function') 
                ? property.bind(target)
                : property;
        }
    });
}

console.log(wrap(function () {}).toString());

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