javascript - 从数组 typescript 内的对象中过滤数据

Question

我有一个数组事件，如下，

[{
    "_id": "5890b4796166c457ffdee243",
    "description": "Adele",
    "name": "Adele",
    "place": {
        "name": "Houston Toyota Center",
        "location": {
            "city": "Houston",
            "country": "United States",
            "latitude": 29.751054939716,
            "longitude": -95.362142762854,
            "state": "TX",
            "street": "1510 Polk St",
            "zip": "77002",
            "_id": "58992aebf2dbf4369c0a0325"
        },
        "id": "200866860532",
        "_id": "5890b47c6166c457ffdee394"
    },
    "start_time": "2016-11-09T20:00:00-0600",
    "id": "1644669702488073"
}, {
    "_id": "5890b4796166c457ffdee242",
    "description": "Please note that delivery will be delayed on all tickets until Friday January 8, 2016. Please adhere to the published ticket limits, which will be strictly enforced. If you exceed these limits, you may have any or all of your orders and tickets cancelled without notice. Please note: Every person, regardless of age, must have a ticket to be admitted to this event. RAIL RIDE EVENT: When you purchase a ticket to a Talking Stick Resort Arena event, you can ride the METRO LIGHT RAIL at no cost for four hours prior to the event through the end of the transit day.",
    "name": "Adele",
    "place": {
        "name": "Talking Stick Resort Arena",
        "location": {
            "city": "Phoenix",
            "country": "United States",
            "latitude": 33.445995372225,
            "longitude": -112.07135782626,
            "state": "AZ",
            "street": "201 E Jefferson St",
            "zip": "85004",
            "_id": "58992aebf2dbf4369c0a0327"
        },
        "id": "53475637527",
        "_id": "5890b4856166c457ffdee427"
    },
    "start_time": "2016-11-21T19:30:00-0700",
    "id": "905384112862937"
}, {
    "_id": "5890b4796166c457ffdee24a",
    "description": "Delivery of tickets will be delayed until 12/31/15",
    "name": "Adele",
    "place": {
        "name": "AmericanAirlines Arena",
        "location": {
            "city": "Miami",
            "country": "United States",
            "latitude": 25.781236943411,
            "longitude": -80.188316709574,
            "state": "FL",
            "street": "601 Biscayne Blvd",
            "zip": "33132",
            "_id": "58992aebf2dbf4369c0a0329"
        },
        "id": "120400119061",
        "_id": "5890b4946166c457ffdee464"
    },
    "start_time": "2016-10-25T19:30:00-0400",
    "id": "445046279020601"
}, {
    "_id": "5890b4796166c457ffdee244",
    "description": "Adele",
    "name": "Adele",
    "place": {
        "name": "Houston Toyota Center",
        "location": {
            "city": "Houston",
            "country": "United States",
            "latitude": 29.751054939716,
            "longitude": -95.362142762854,
            "state": "TX",
            "street": "1510 Polk St",
            "zip": "77002",
            "_id": "58992aebf2dbf4369c0a032b"
        },
        "id": "200866860532",
        "_id": "5890b47c6166c457ffdee354"
    },
    "start_time": "2016-11-08T20:00:00-0600",
    "id": "1662607760654203"
}, {
    "_id": "5890b4796166c457ffdee245",
    "description": "Delivery will be delayed until Oct 2, 2016.",
    "name": "Adele",
    "place": {
        "name": "American Airlines Center",
        "location": {
            "city": "Dallas",
            "country": "United States",
            "latitude": 32.790485550848,
            "longitude": -96.810278349053,
            "state": "TX",
            "street": "2500 Victory Ave",
            "zip": "75219",
            "_id": "58992aebf2dbf4369c0a032d"
        },
        "id": "26606856232",
        "_id": "5890b47b6166c457ffdee2e4"
    },
    "start_time": "2016-11-02T20:00:00-0500",
    "id": "649884741817020"
}]

如何使用 typescript 从上面的 json 中获取所有城市？

我已经尝试过了，

this.eventsFiltered = this.events.filter(
          book => book.place.location.city);

Answer 1

试试这个:

this.eventsFiltered = this.events.map(
              book => book.place.location.city);

编辑

i want to filter the events which has speficic places?

let events = [{
"_id": "5890b4796166c457ffdee243",
"description": "Adele",
"name": "Adele",
"place": {
    "name": "Houston Toyota Center",
    "location": {
        "city": "Houston",
        "country": "United States",
        "latitude": 29.751054939716,
        "longitude": -95.362142762854,
        "state": "TX",
        "street": "1510 Polk St",
        "zip": "77002",
        "_id": "58992aebf2dbf4369c0a0325"
    },
    "id": "200866860532",
    "_id": "5890b47c6166c457ffdee394"
},
"start_time": "2016-11-09T20:00:00-0600",
"id": "1644669702488073"
}, {
"_id": "5890b4796166c457ffdee242",
"description": "Please note that delivery will be delayed on all tickets until Friday January 8, 2016. Please adhere to the published ticket limits, which will be strictly enforced. If you exceed these limits, you may have any or all of your orders and tickets cancelled without notice. Please note: Every person, regardless of age, must have a ticket to be admitted to this event. RAIL RIDE EVENT: When you purchase a ticket to a Talking Stick Resort Arena event, you can ride the METRO LIGHT RAIL at no cost for four hours prior to the event through the end of the transit day.",
"name": "Adele",
"place": {
    "name": "Talking Stick Resort Arena",
    "location": {
        "city": "Phoenix",
        "country": "United States",
        "latitude": 33.445995372225,
        "longitude": -112.07135782626,
        "state": "AZ",
        "street": "201 E Jefferson St",
        "zip": "85004",
        "_id": "58992aebf2dbf4369c0a0327"
    },
    "id": "53475637527",
    "_id": "5890b4856166c457ffdee427"
},
"start_time": "2016-11-21T19:30:00-0700",
"id": "905384112862937"
}, {
"_id": "5890b4796166c457ffdee24a",
"description": "Delivery of tickets will be delayed until 12/31/15",
"name": "Adele",
"place": {
    "name": "AmericanAirlines Arena",
    "location": {
        "city": "Miami",
        "country": "United States",
        "latitude": 25.781236943411,
        "longitude": -80.188316709574,
        "state": "FL",
        "street": "601 Biscayne Blvd",
        "zip": "33132",
        "_id": "58992aebf2dbf4369c0a0329"
    },
    "id": "120400119061",
    "_id": "5890b4946166c457ffdee464"
},
"start_time": "2016-10-25T19:30:00-0400",
"id": "445046279020601"
}, {
"_id": "5890b4796166c457ffdee244",
"description": "Adele",
"name": "Adele",
"place": {
    "name": "Houston Toyota Center",
    "location": {
        "city": "Houston",
        "country": "United States",
        "latitude": 29.751054939716,
        "longitude": -95.362142762854,
        "state": "TX",
        "street": "1510 Polk St",
        "zip": "77002",
        "_id": "58992aebf2dbf4369c0a032b"
    },
    "id": "200866860532",
    "_id": "5890b47c6166c457ffdee354"
},
"start_time": "2016-11-08T20:00:00-0600",
"id": "1662607760654203"
}, {
"_id": "5890b4796166c457ffdee245",
"description": "Delivery will be delayed until Oct 2, 2016.",
"name": "Adele",
"place": {
    "name": "American Airlines Center",
    "location": {
        "city": "Dallas",
        "country": "United States",
        "latitude": 32.790485550848,
        "longitude": -96.810278349053,
        "state": "TX",
        "street": "2500 Victory Ave",
        "zip": "75219",
        "_id": "58992aebf2dbf4369c0a032d"
    },
    "id": "26606856232",
    "_id": "5890b47b6166c457ffdee2e4"
},
"start_time": "2016-11-02T20:00:00-0500",
"id": "649884741817020"
}];

let eventsFiltered = events.map(
          book => book.place.location.city);

console.log(eventsFiltered);
let city = 'Houston';
let eventsCt = events.filter(book => book.place.location.city == city);
console.log('2nd question');
console.log(eventsCt);

编辑2

i have a field named "parent" which is an array of string. i already have a string named "12344" which is a part of array parent. how do i check if the events.parent cotains this string and filter those objects

let p = '1234';
let eventsF = events.filter(book => book.parent && Array.isArray(book.parent)&& book.parent.indexOf(p) !== -1);