JavaScript Array filter() 方法 筛选过滤去重

filter() 方法创建一个新的数组，新数组中的元素是通过检查指定数组中符合条件的所有元素。
通过一定的条件逻辑可以筛选过滤去重。

var weathers = [ {
        "curTemp" : "35",
        "temp" : "22~34",
        "weather" : "晴",
        "wind" : "东北风4级",
        "cname" : "黄帝故里",
        "name" : "huangdiguli",
        "aqi" : "32",
        "aqi1" : "优",
        "humidity" : "41%",
        "type" : "2"
    }, {
        "curTemp" : "29",
        "temp" : "22~34",
        "weather" : "多云",
        "wind" : "东北风4级",
        "cname" : "世纪欢乐园",
        "name" : "shijihuanleyuan",
        "aqi" : "61",
        "aqi1" : "良",
        "humidity" : "36%",
        "type" : "2"
    }, {
        "curTemp" : "32",
        "temp" : "22~34",
        "weather" : "多云",
        "wind" : "东北风4级",
        "cname" : "方特欢乐世界",
        "name" : "fangtehuanleshijie",
        "aqi" : "42",
        "aqi1" : "优",
        "humidity" : "46%",
        "type" : "2"
    }, {
        "curTemp" : "29",
        "temp" : "22~34",
        "weather" : "多云",
        "wind" : "东北风4级",
        "cname" : "城隍庙·文庙",
        "name" : "chenghuangmiaowenmiao",
        "aqi" : "61",
        "aqi1" : "良",
        "humidity" : "36%",
        "type" : "2"
    }, {
        "curTemp" : "32",
        "temp" : "21~33",
        "weather" : "晴",
        "wind" : "东北风2级",
        "cname" : "中岳庙",
        "name" : "zhongyuemiao",
        "aqi" : "38",
        "aqi1" : "优",
        "humidity" : "34%",
        "type" : "2"
    }, {
        "curTemp" : "32",
        "temp" : "22~34",
        "weather" : "多云",
        "wind" : "东北风4级",
        "cname" : "农业高新科技园",
        "name" : "nongyegaoxinkejiyuan",
        "aqi" : "42",
        "aqi1" : "优",
        "humidity" : "46%",
        "type" : "2"
    }, {
        "curTemp" : "29",
        "temp" : "22~34",
        "weather" : "多云",
        "wind" : "东北风4级",
        "cname" : "郑州海洋馆",
        "name" : "zhengzhouhaiyangguan",
        "aqi" : "60",
        "aqi1" : "良",
        "humidity" : "36%",
        "type" : "2"
    }, {
        "curTemp" : "29",
        "temp" : "22~34",
        "weather" : "多云",
        "wind" : "东北风4级",
        "cname" : "樱桃沟景区",
        "name" : "yingtaogoujingqu",
        "aqi" : "61",
        "aqi1" : "良",
        "humidity" : "36%",
        "type" : "2"
    }, {
        "curTemp" : "32",
        "temp" : "21~33",
        "weather" : "晴",
        "wind" : "东北风2级",
        "cname" : "嵩阳书院",
        "name" : "songyangshuyuan",
        "aqi" : "38",
        "aqi1" : "优",
        "humidity" : "34%",
        "type" : "2"
    }, {
        "curTemp" : "36",
        "temp" : "22~33",
        "weather" : "多云",
        "wind" : "东北风4级",
        "cname" : "伏羲山神仙洞",
        "name" : "fuxishanshenxiandong",
        "aqi" : "42",
        "aqi1" : "优",
        "humidity" : "35%",
        "type" : "2"
    }, {
        "curTemp" : "36",
        "temp" : "22~33",
        "weather" : "多云",
        "wind" : "东北风4级",
        "cname" : "伏羲山大峡谷",
        "name" : "fuxishandaxiagu",
        "aqi" : "40",
        "aqi1" : "优",
        "wuranwu" : "暂无",
        "pm25" : "暂无",
        "pm10" : "暂无",
        "humidity" : "35%",
        "type" : "2"
    }, {
        "curTemp" : "32",
        "temp" : "22~34",
        "weather" : "多云",
        "wind" : "东北风3级",
        "wind6" : "西南风",
        "cname" : "古柏渡旅游区",
        "name" : "gubaidulvyouqu",
        "aqi" : "43",
        "aqi1" : "优",
        "humidity" : "37%",
        "type" : "2"
    }, {
        "curTemp" : "35",
        "temp" : "22~34",
        "weather" : "小雨",
        "wind" : "东北风4级",
        "cname" : "具茨山景区",
        "name" : "jucishanjingqu",
        "aqi" : "32",
        "aqi1" : "优",
        "humidity" : "41%",
        "type" : "2"
    }, {
        "curTemp" : "29",
        "temp" : "22~34",
        "weather" : "晴",
        "wind" : "东北风4级",
        "cname" : "富景生态世界",
        "name" : "fujingshengtaishijie",
        "aqi" : "44",
        "aqi1" : "优",
        "humidity" : "36%",
        "type" : "2"
    } ];
    //过滤晴天的景区
    var sunshine = weathers.filter((item) => {return item.weather === '晴'});
    //也可以这样写
    var sun = weathers.filter(function(item) {
        return item.weather === '晴';
    });
    console.log(sunshine);
    console.log(sun);
    //数组去重
    var language = ['Java','JavaScript','Java','C++','JavaScript'];
    var single = language.filter(function(item, index, language) {
        //当前元素，在原始数组中的第一个索引==当前索引值，否则返回当前元素
        return language.indexOf(item, 0) === index;
    });
    console.log(single)