How to get all array objects of an array

Question

There is an target array inside of an array object:

[ 
  { 
    _id: 'main1',
    target: [
      { _id: '1', foo: [bar] },
      { _id: '2', foo: [bar] }
    ]
  },
  { 
    _id: 'main2',
    target: [
      { _id: '3', foo: [bar] },
      { _id: '4', foo: [bar] }
    ]
  }
]

I need to get all target objects as one array:

Needed result

targets: [
  { _id: '1', foo: [bar] },
  { _id: '2', foo: [bar] }
  { _id: '3', foo: [bar] },
  { _id: '4', foo: [bar] }
]

I tried to use a map()

array.map(item => item.target)

But this results in a nested array like: [ [ { _id: '1', foo: [bar] } ] ]

var array = [ 
      { 
        _id: 'main1',
        target: [
          { _id: '1', foo: ["bar"] },
          { _id: '2', foo: ["bar"] }
        ]
      },
      { 
        _id: 'main2',
        target: [
          { _id: '3', foo: ["bar"] },
          { _id: '4', foo: ["bar"] }
        ]
      }
    ]

console.log(
  array.map(item => item.target)
)

If you have a library like underscore or lodash, you could use the flatmap function — Dimitri
– Dimitri, Commented Jun 6, 2018 at 15:16

Eddie · Accepted Answer · 2018-06-06 15:15:12Z

3

You can use concat to join arrays. Use spread operator and map to loop thru the array.

let arr = [{_id:'main1',target:[{_id:'1',foo:['bar']},{_id:'2',foo:['bar']}]},{_id:'main2',target:[{_id:'3',foo:['bar']},{_id:'4',foo:['bar']}]}];
let result = [].concat(...arr.map(o => o.target));

console.log(result);

answered Jun 6, 2018 at 15:15

Eddie

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Comments

amrender singh · Accepted Answer · 2018-06-06 15:16:06Z

0

var arr = [ 
  { 
    _id: 'main1',
    target: [
      { _id: '1', foo: ["bar"] },
      { _id: '2', foo: ["bar"] }
    ]
  },
  { 
    _id: 'main2',
    target: [
      { _id: '3', foo: ["bar"] },
      { _id: '4', foo: ["bar"] }
    ]
  }
]
var result =  arr.reduce((a,o) => a.concat(o.target), []);
console.log(result);

answered Jun 6, 2018 at 15:16

amrender singh

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1 Comment

Pablo Barría Urenda Over a year ago

I don't know why someone downvoted this. This is a correct answer (see my similar one as well). You can use the ... operator instead of concat.

mscdeveloper · Accepted Answer · 2018-06-06 15:21:44Z

0

var array = [
      {
        _id: 'main1',
        target: [
          { _id: '1', foo: ["bar"] },
          { _id: '2', foo: ["bar"] }
        ]
      },
      {
        _id: 'main2',
        target: [
          { _id: '3', foo: ["bar"] },
          { _id: '4', foo: ["bar"] }
        ]
      }
    ] ;

  var result=[];
  for(var key in array){
  	 target=array[key].target;
  	 for(var kt in target){
  	 	 result.push(target[kt]);
  	 }
  }

  console.log(result);

answered Jun 6, 2018 at 15:21

mscdeveloper

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Comments

zfrisch · Accepted Answer · 2018-06-06 15:38:56Z

0

You can use the reduce method ( Array.prototype.reduce )

This answer checks for the property target before concatenating.

let targets = obj_arr.reduce((a,c)=>c.target&&a.concat(c.target),[]);

let obj_arr = [{
    _id: 'main1',
    target: [{
        _id: '1',
        foo: [""]
      },
      {
        _id: '2',
        foo: [""]
      }
    ]
  },
  {
    _id: 'main2',
    target: [{
        _id: '3',
        foo: [""]
      },
      {
        _id: '4',
        foo: [""]
      }
    ]
  }
]

let targets = obj_arr.reduce((accumulator, current_value) =>
      current_value.target&&accumulator.concat(current_value.target), []);


console.log(targets);

edited Jun 6, 2018 at 15:38

answered Jun 6, 2018 at 15:22

zfrisch

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Comments

Shubhanu Sharma · Accepted Answer · 2018-06-06 15:45:32Z

0

var foo = [
  {
    "_id": "main1",
    "target": [
      {
        "_id": "1",
        "foo": "[bar]"
      },
      {
        "_id": "2",
        "foo": "[bar]"
      }
    ]
  },
  {
    "_id": "main2",
    "target": [
      {
        "_id": "3",
        "foo": "[bar]"
      },
      {
        "_id": "4",
        "foo": "[bar]"
      }
    ]
  }
]
var bar = [];
foo.map(function(val) {	
	bar = bar.concat(val.target);
})
console.log(bar)

answered Jun 6, 2018 at 15:45

Shubhanu Sharma

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Comments

zeh · Accepted Answer · 2018-06-06 17:14:05Z

0

You can use reduce(). It loops through an Array (similarly to map()) but creating a new result as it goes.

array.reduce((result, current) => {
    result = [...result, ...current.target]
    return result;
}, []);

Or, if you cannot use spreads, you can use concat() instead:

array.reduce((result, current) => {
    result = result.concat(current.target);
    return result;
}, []);

edited Jun 6, 2018 at 17:14

zeh

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answered Jun 6, 2018 at 15:18

Pablo Barría Urenda

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