filter方法和find方法

数组有一些列的方法，比如：

map()
find()
filter()
every()
forEach()

今天我们只看filter方法和find()

 cityShowClickEvent(index) {
        //console.log("点击城市的每一项");
        //获取城市码
        let cityCode = this.state.cityList[index].cityCode;
        console.log("城市码：",cityCode);
        //console.log("cityList",this.state.cityList);
        let filter_list = this.state.cityList.filter((item,index)=>{
            return item.cityCode === cityCode;
        })
        let find_list = this.state.cityList.find((item,index)=>{
            return item.cityCode === cityCode;
        })
        console.log("filter_list",filter_list);
        console.log("find_list",find_list);
        //console.log(list);
        let cityName = find_list.name;
        //console.log("cityName",cityName);
        this.setState({
            city: cityName,
            city_show: false,
            contentList: filter_list,
        })
    }