How map and filter over array of objects?

Question

sorry guys but i have a dummy question.. i need to iterate objects from a json response and obtain only those how meet some conditions.. the response is like this:

  result = [
      {
        "type": "EVENT",
        "id": "001",
        "tags": [
            {
            "id": "98765",
            "name": "home"
            }
        ]
      },
      {
        "type": "EVENT",
        "id": "002",
        "tags": [
            {
            "id": "7654",
            "name": "contact"
            }
        ]
      },
      {
        "type": "EVENT",
        "id": "003",
        "tags": []
      }
    ]

I need to use only those whose type is 'event' and name properties in tags be home.

I tried map and filter, but I do not get the desired result

const eventType = result.filter(type => type.type == 'EVENT')
 const nameFilter = 
    eventType.map(item => item.tags)
    .filter(sub => sub.length) // remove empty []
    .map(subarray => subarray.map(element =>  element.name )
    .filter(element => element == 'home'));

result:

 [
  ['home'], // dosen t work for me, because need all the object
  [],
  []
 ]

Eddie · Accepted Answer · 2019-05-11 13:46:39Z

3

You can use filter to loop thru the array. Use some to check if at least one element in the tags array has a property name with value of "home":

result.filter(o => o.type === "EVENT" && o.tags.some(s => s.name === "home"));

Demo:

let result = [{"type":"EVENT","id":"001","tags":[{"id":"98765","name":"home"}]},{"type":"EVENT","id":"002","tags":[{"id":"7654","name":"contact"}]},{"type":"EVENT","id":"003","tags":[]}];

let filtered = result.filter(o => o.type === "EVENT" && o.tags.some(s => s.name === "home"));

console.log( filtered );

edited May 11, 2019 at 13:46

answered May 11, 2019 at 13:01

Eddie

26.8k6 gold badges39 silver badges59 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Hien Nguyen · Accepted Answer · 2019-05-11 13:48:57Z

You only need filter() and use find() or some() to check exist name in tags.

var filter = result.filter(c=> c.type == "EVENT" && c.tags.find(d=>d.name == 'home'));
var filter = result.filter(c=> c.type == "EVENT" && c.tags.some(d=>d.name == 'home'));

let result=  [
      {
        "type": "EVENT",
        "id": "001",
        "tags": [
            {
            "id": "98765",
            "name": "home"
            }
        ]
      },
      {
        "type": "EVENT",
        "id": "002",
        "tags": [
            {
            "id": "7654",
            "name": "contact"
            }
        ]
      },
      {
        "type": "EVENT",
        "id": "003",
        "tags": []
      }
    ]
    
    var filter = result.filter(c=> c.type == "EVENT" && c.tags.find(d=>d.name == 'home'));
    
    console.log(filter);

Gustavo Maloste · Accepted Answer · 2019-05-11 13:12:06Z

-1

if you simply want to select elements from the root array then filter is the appropriate way to do. if you want to also transform the result (say, select the TAG object), you may use flatMap

result.flatMap( e => (e.type == 'EVENT' && e.tags.some(t => t.name==='home')) ? e.tags : [] )

answered May 11, 2019 at 13:12

Gustavo Maloste

1644 bronze badges

Collectives™ on Stack Overflow

How map and filter over array of objects?

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related