Rearranging javascript object structure

Question

I am looking at an object with the following structure:

[
  [
    {
      "attr1":"1",
      "attr2":"2",
      "attr3":"3"
    }
  ],
  [
    {
      "attr1":"1",
      "attr2":"2",
      "attr3":"3"
    }
  ],
  [
    {
      "attr1":"1",
      "attr2":"2",
      "attr3":"3"
    }
  ]
]

Just focusing on the structure of it, all I need to do with this object is to re-arrange it so that it ends up with the following structure:

[
  {
    "attr1":"1",
    "attr2":"2",
    "attr3":"3"
  },
  {
    "attr1":"1",
    "attr2":"2",
    "attr3":"3"
  },
  {
    "attr1":"1",
    "attr2":"2",
    "attr3":"3"
  }
]

How can this be done in either pure Javascript or in core jQ library?

So you just want to take the first element of each inner array? You could get away with just `myArray.map(x=>x[0])`. — Eric Dobbs, Apr 18 '17 at 19:48

score 2 · Accepted Answer · answered Apr 18 '17 at 19:49

2

So, you just need to remove the second-level arrays. Easily done with Array.map().

var old = [
  [
    {
      "attr1":"1",
      "attr2":"2",
      "attr3":"3"
    }
  ],
  [
    {
      "attr1":"1",
      "attr2":"2",
      "attr3":"3"
    }
  ],
  [
    {
      "attr1":"1",
      "attr2":"2",
      "attr3":"3"
    }
  ]
];

// Map loops through an array and returns a new array filled with whatever the 
// supplied callback function returns. 
var newArry = old.map(function(value){
  // Get the first object stored in the second-level array, but not the array itself
  return value[0];  
});

console.log(newArry);

answered Apr 18 '17 at 19:49

Scott Marcus

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you expect only one item in an array, it does not look very versatile. – Nina Scholz Apr 18 '17 at 20:09
@NinaScholz True, but the OP was specific when he said what the structure he was dealing was. – Scott Marcus Apr 18 '17 at 20:10

score 0 · Answer 2 · answered Apr 18 '17 at 19:48

0

Array#reduce may be helpful.

var arr = [[{"attr1":"1","attr2":"2","attr3":"3"}],[{"attr1":"1","attr2":"2","attr3":"3"}],[{"attr1":"1","attr2":"2","attr3":"3"}]], 
    res = arr.reduce((a,b) => a.concat(b));

    console.log(res);

answered Apr 18 '17 at 19:48

kind user

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Nina Scholz · Answer 3 · 2017-04-20T11:35:13.237

0

You could use Array#concat with a spread syntax ....

var data = [[{ attr1: "1", attr2: "2", attr3: "3" }], [{ attr1: "1", attr2: "2", attr3: "3" }], [{ attr1: "1", attr2: "2", attr3: "3" }]],
    flat = [].concat(...data);

console.log(flat);

.as-console-wrapper { max-height: 100% !important; top: 0; }

ES5

var data = [[{ attr1: "1", attr2: "2", attr3: "3" }], [{ attr1: "1", attr2: "2", attr3: "3" }], [{ attr1: "1", attr2: "2", attr3: "3" }]],
    flat = [].concat.apply([], data);

console.log(flat);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Apr 20 '17 at 11:35

answered Apr 18 '17 at 19:49

Nina Scholz

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@ScottMarcus, the second should work for older javascript implementations. – Nina Scholz Apr 18 '17 at 20:08

Rearranging javascript object structure

3 Answers3