Flatten a nested objects to one dimensional array javascript

Question

I have a nested objects in this structure:

myArray = {
  "D": {
    "U": {
      "A300": "B300",
      "A326": "B326",
      "A344": "B344",
      "A345": "B345"
    },
    "P": {
      "A664": "B664",
      "A756": "B756"
    }
  },
  "I": {
    "U": {
      "A300": "B300",
      "A326": "B326"
    },
    "P": {
      "A756": "B756"
    }
  }
};

I am trying to get the data out of it to be only one dimensional (Flatten). I tried the code below but it doesn't work:

var myNewArray = [].concat.apply([], myArray);

and

var myNewArray = myArray.reduce(function(prev, curr) {
  return prev.concat(curr);
});

I want myNewArray to have ["B300","B326","B344","B345","B664","B756"]

Already tried that and it gives an error about the reduce function — SMH
– SMH, Commented Nov 21, 2017 at 0:54
@Andy Doesn't work if the elements aren't all in myArray[0][0][0]: jsfiddle.net/barmar/ryfwudqd/2 — Barmar
– Barmar, Commented Nov 21, 2017 at 0:57

Titus · Accepted Answer · 2017-11-21 01:49:54Z

2

You can do something like this:

var myArray = [];
myArray[0] = [];
myArray[0][0] = [];
myArray[0][0][0] = [];
myArray[0][0][1] = [];
myArray[0][1] = [];
myArray[0][1][0] = [];

myArray[0][0][0][0] = "abc1";
myArray[0][0][0][1] = "abc2";
myArray[0][0][1][0] = "abc3";
myArray[0][1][0][1] = "abc4";
myArray[0][1][0][1] = "abc5";


function flat(acc, val){
  if(Array.isArray(val)){
     acc = acc.concat(val.reduce(flat, []));
  }else{
   acc.push(val);
  }
  return acc;
}

var newMyArray = myArray.reduce(flat, []);
console.log(newMyArray);

What this does is to recursively reduce all the inner values that are arrays.

It seems that you're dealing with an object. The previous title of your question and the name of the variable are misleading.

In any case, flattening an object is a very similar process.

var myArray = {"D":{"U":{"A300":"B300","A326":"B326","A344":"B344","A345":"B345"},"P":{"A664":"B664","A756":"B756"}},"I":{"U":{"A300":"B300","A326":"B326"},"P":{"A756":"B756"}}};

function flatObj(obj){
   return Object.keys(obj).reduce(function(acc, key){
     if(typeof obj[key] === "object"){
        acc = acc.concat(flatObj(obj[key]));
     }else{
        acc.push(obj[key]);
     }
     return acc;
   }, []);
}


var newMyArray = flatObj(myArray);
console.log(newMyArray);

edited Nov 21, 2017 at 1:49

answered Nov 21, 2017 at 0:59

Titus

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11 Comments

Barmar Over a year ago

Looks nice, except he's changed the question to an array of objects, not array of arrays.

Titus Over a year ago

@SMH I've edited my answer to make to add an example for flattening an object.

Titus Over a year ago

@Barmar I've saw that, I've edited my answer to address it.

charlietfl Over a year ago

Might need a unique filter also based on expected results shown. OP needs to clarify

Titus Over a year ago

@charlietfl Yes, they seem to be sorted in ascending order.

|

JJJ · Accepted Answer · 2017-11-21 02:22:20Z

2

I just wanted to add my 2 cents since I was following this question and working on an answer before I left work. I'm home now so I want to post what I came up with.

const obj = {
  x1: { 
    y1: {
      z1: {
          h1: 'abc',
          h2: 'def'
          },
      z2: {
          h1: 123,
          h2: 456
         }
        }
  }
}

const valAll = getPropValuesAll(obj)
console.log(valAll)

function getPropValuesAll(obj, result = []){
  for(let k in obj){
    if(typeof obj[k] !== 'object'){
    	result.push(obj[k])
        continue
    }
    getPropValuesAll(obj[k], result)
  }
  return result
}

answered Nov 21, 2017 at 2:22

JJJ

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Comments

sapics · Accepted Answer · 2017-11-21 01:11:33Z

0

It would be easy and safe answer.

var myArray = [["abc1"],[["abc2",,"abc3"]],"abc4",{"r5": "abc5", "r6": "abc6"}];
var myNewArray = [];
function flatten(arr){
  if(Array.isArray(arr)){
    for(var i = 0, l = arr.length; i < l; ++i){
      if(arr[i] !== undefined){
        flatten(arr[i])
      }
    }
  } else if (typeof arr === 'object') {
    for(var key in arr){
      if(arr.hasOwnProperty(key)){
        flatten(arr[key])
      }
    }
  } else {
    myNewArray.push(arr)
  }
}
flatten(myArray)

console.log(myNewArray)

edited Nov 21, 2017 at 1:11

answered Nov 21, 2017 at 1:01

sapics

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