代理对象重复值。

使用Set数据结构去重。

示例代码：

const handler = { get: (target, prop) => { console.log(Getting value of ${prop}.); return target[prop]; },

set: (target, prop, value) => { if (target[prop] === value) { console.log(Value of ${prop} already set to ${value}.); return true; // return true to indicate successful set } console.log(Setting value of ${prop} to ${value}.); target[prop] = value; return true; // return true to indicate successful set } };

const myObj = {prop1: 1, prop2: 2}; const myProxy = new Proxy(myObj, handler);

console.log(myProxy.prop1); // logs "Getting value of prop1." then 1 myProxy.prop1 = 1; // logs "Value of prop1 already set to 1." but does not set value myProxy.prop1 = 3; // logs "Setting value of prop1 to 3." and sets value to 3