Iterate over two arrays and return an array of objects

Question

I have two arrays, one with names and another with id's that relate to the names.

arr1 = ["Bob Jones", "Steven Simon", "Green Tea"];
arr2 = [10, 8, 13];

The Id's in arr2 correspond to the names in arr1. For example, Bob Jones has an Id of 10. What I would like to do is return a single array of objects as follows:

[
  {
    Id: 10,
    Name: Bob Jones
  },
  {
    Id: 8,
    Name: Steven Simon
  },
  {
    Id: 13,
    Name: Green Tea
  }
]

I have attempted to use Object.defineproperties as per the code below.

const myOjbect = {};

Object.defineProperties(myObject, {
  name: {
    value: arr1[0],
    enumerable: true,
    writable: false,
  },
  id: {
    value: arr2[0],
    enumerable: true,
    writable: true,
  },
})

This provides the expected result for first item in the array but I also need the subsequent items in the array to be included in the object (not just the first one).

T.J. Crowder · Accepted Answer · 2019-05-14 10:20:49Z

There's no need for Object.defineProperty/defineProperties, you can just create the objects with initializer (aka "literal") syntax in a map callback:

const result = arr1.map((Name, index) => ({Id: arr2[index], Name}));

That works because map calls the callback function with the entry's value (the name in this case) and also its index (and also the object you called map on, but we're not using that), so we use the name directly and get the ID from the equivalent location in arr2.

In JavaScript, it would be more idiomatic for those property names to be in lower case:

const result = arr1.map((name, index) => ({id: arr2[index], name}));

Live Example:

const arr1 = ["Bob Jones", "Steven Simon", "Green Tea"];
const arr2 = [10, 8, 13];
const result = arr1.map((name, index) => ({id: arr2[index], name}));
console.log(result);

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

If you need to limit yourself to ES5-level features instead of the ES2015+ features I've used above:

var result = arr1.map(function(name, index) {
    return {id: arr2[index], name: name};
});

Live Example:

var arr1 = ["Bob Jones", "Steven Simon", "Green Tea"];
var arr2 = [10, 8, 13];
var result = arr1.map(function(name, index) {
    return {id: arr2[index], name: name};
});
console.log(result);

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

Nina Scholz · Accepted Answer · 2019-05-14 11:43:42Z

1

You could take an object with the wanted key and theit values and reduce this object by mapping the object with their new properties. This works for an arbitray count of keys. The arrays have to have the same length.

var Id = [10, 8, 13],
    Name = ["Bob Jones", "Steven Simon", "Green Tea"],
    result = Object.entries({ Id, Name }).reduce((r, [k, a]) => 
        a.map((v, i) => Object.assign(r[i] || {}, { [k]: v })),
        []
    );

console.log(result);

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

answered May 14, 2019 at 11:43

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Comments

Vivekanand Panda · Accepted Answer · 2019-05-14 10:26:49Z

0

Try using forEach loop

var arr1 = ['Bob Jones', 'Steven Simon', 'Green Tea']; 
var arr2 = [10, 8, 13];
var a=[];
arr1.forEach((e,i)=>a.push({id:arr2[i], name:e}))
console.log(a)

edited May 14, 2019 at 10:26

Vivekanand Panda

88513 silver badges24 bronze badges

answered May 14, 2019 at 10:22

ellipsis

12.2k2 gold badges19 silver badges33 bronze badges

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