Merge js objects whose parents have variable key names

Question

I have an object that has the following structure:

mymain = { 
name1: [ {key1: number, key2: "string"},{key1: number, key2: "string"} ],
name2: [ {key1: number, key2: "string"},{key1: number, key2: "string"} ],
name3: [ {key1: number, key2: "string"},{key1: number, key2: "string"} ]
}

The top level items (name1, name2, name3) will vary in amount and key names.

I want to merge all the objects (which are also variable in number and values, but all have the same key structure) UNDER these names into one large object that will look like this:

Allconcat = [{key1: number, key2: "string"},{key1: number, key2: "string"},{key1: number, key2: "string"},{key1: number, key2: "string"},{key1: number, key2: "string"},{key1: number, key2: "string"}]

I have tried extracting the names of the top level items and them looping to concatenate the objects but that gives the wrong number of items:

var names = Object.keys(mymain)
    var firstname = names[0]
    names.shift() // should remove first item
    var firstObj = mymain[firstname] // name1 object
    var Allconcat
    console.log(firstObj) // correctly shows name1 with 2 keys
    for (var r = 0, rlen = names.length; r < rlen; r++) {
      Allconcat = firstObj.concat(mymain[names[r]])
    }
    console.log(Allconcat) // shows 4 objects, missing 2 in the middle, first and last are there

shifting or not shifting makes no difference, and I always end up with some of the elements missing in the middle.

CertainPerformance · Accepted Answer · 2019-05-01 09:42:34Z

2

One option is to take the Object.values of the mymain object, and flatten the array:

const mymain = { 
  name1: [ {key1: 'number', key2: "string"},{key1: 'number', key2: "string"} ],
  name2: [ {key1: 'number', key2: "string"},{key1: 'number', key2: "string"} ],
  name3: [ {key1: 'number', key2: "string"},{key1: 'number', key2: "string"} ]
};

const Allconcat = Object.values(mymain).flat();
console.log(Allconcat);

Or, if you can't use .flat(), then spread into concat:

const mymain = { 
  name1: [ {key1: 'number', key2: "string"},{key1: 'number', key2: "string"} ],
  name2: [ {key1: 'number', key2: "string"},{key1: 'number', key2: "string"} ],
  name3: [ {key1: 'number', key2: "string"},{key1: 'number', key2: "string"} ]
};

const Allconcat = [].concat(...Object.values(mymain));
console.log(Allconcat);

answered May 1, 2019 at 9:42

CertainPerformance

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