SOURCE

function copyProperties(target, source) {
    for (let key of Reflect.ownKeys(source)) {
      	if (['constructor', 'prototype', 'name'].indexOf(key) < 0) {
           	let desc = Object.getOwnPropertyDescriptor(source, key);
            Object.defineProperty(target, key, desc);
        }
    }
}

function mixin(...mixins) {
    class Mixin {
        constructor() {
            mixins.forEach(
                mixin => copyProperties(this, new mixin()) // 拷贝实例属性
        		) 
        }
    }
    mixins.forEach(
        mixin => {
            copyProperties(Mixin, mixin); // 拷贝静态属性
            copyProperties(Mixin.prototype, mixin.prototype); // 拷贝原型属性
        }
    )

    return Mixin;
}

class Parent1 {
    say(name) {
        return name;
    }
}

class Parent2 {
    walk(type) {
        return "walk" + type;
    }
}

class Child extends mixin(Parent1, Parent2) {
    do() {
        return "child do---"
    }
}

const c = new Child();
console.log(c.do());
console.log(c.say("child"));
console.log(c.walk("A"));