JSON.parse()、JSON.stringify()实现数据深拷贝

       function deepCopy(obj){
            let before = JSON.stringify(obj),
            afterCopy = JSON.parse(before);
            return afterCopy
        }

        let before_=["zhaoqian",27,"shanghai",13000],
            afterCopy_=deepCopy(before_);
            afterCopy_[2] = "上海";
        console.log(before_,afterCopy_);