proxy代理

porxy 代理在爬虫方面和HOOK,的功能差不多，都是监控对象属性

1. 单对象代理

document = new Proxy(document,{
    get(target,p,receiver){
        let res = Reflect.get(target,p,receiver)
        console.log(`对象document,调用属性/方法: ${p},
属性/方法类型: ${typeof p} ,值: ${res},值类型: ${typeof res}`)
        return res
    },
    set(target, p, value, receiver) {
        console.log(`对象document,设置属性/方法: ${p},
属性/方法类型: ${typeof p} ,值:${value},值类型: ${typeof target[p]}`)
        return Reflect.set(target,p,value,receiver)
    }
})

document.referrer = 'https://www.jianshu.com/'

console.log(document.referrer)

2. 对象以数组方式加入代理

function SetProxy(proxyObjs) {
    for (let i = 0; i < proxyObjs.length; i++) {
        const handler = `{
          get: function(target, property, receiver) {
            console.log("方法:", "get  ", "对象:", "${proxyObjs[i]}", "  属性:", property, "  属性类型：", typeof property, ", 属性值：", target[property]);
            return target[property];
          },
          set: function(target, property, value, receiver) {
            console.log("方法:", "set  ", "对象:", "${proxyObjs[i]}", "  属性:", property, "  属性类型：", typeof property, ", 属性值：", value, ", 属性值类型：", typeof target[property]);
            return Reflect.set(...arguments);
          }
        }`;
        eval(`try {
            ${proxyObjs[i]};
            ${proxyObjs[i]} = new Proxy(${proxyObjs[i]}, ${handler});
        } catch (e) {
            ${proxyObjs[i]} = {};
            ${proxyObjs[i]} = new Proxy(${proxyObjs[i]}, ${handler});
        }`);
    }
}

/* 
    传入需要代理的对象: 
    window,localStorage,document,navigator,screen,location,sessionStorage
   这里对象很多,需要根据实际情况来补,以下是常用的补环境
*/
SetProxy(
["window","localStorage","document","navigator","screen","location","sessionStorage"]
)

当使用proxy 代理之后，所有经过属性方法取值设值都会被监控到,这在爬虫补环境中非常有用