How to get value from index property in javascript?

Question

Here is my code:

const array1 = [{a: 'abc', b: 'cd'}, {a: 'abc', b: 'xyz'}, {a: 'abc', 
b: 'mno'}];
let obj = array1.reduce(function(result, item, index){
    result[index] = item
  return result;
}, {});

let dealId = 123;
let value = {};
let array2 = [];
for (var property in obj) {
   value[dealId] = array2.push(obj[property]);
}
console.log(value)

The output of this is Object { 123: 3 }

But I want and this is what I was expecting. Object { 123: [{a: 'abc', b: 'cd'}, {a: 'abc', b: 'xyz'}, {a: 'abc', b: 'mno'}] }

Why am I getting 3 instead of an array? How to get the array?

Push returns the new length of the array. Move the assignment outside the loop. Also, you can simply use Object.values(obj) instead (with a difference that inherited properties won't be listed). — riv
– riv, Commented Aug 29, 2018 at 8:18

riv · Accepted Answer · 2018-08-29 08:22:07Z

1

Array.prototype.push returns the new length of the array, not the array itself. Your loop assigns the values 1, 2 and 3 to the same value[dealId].

Instead, you can move the assignment outside the loop:

for (var property in obj) {
   array2.push(obj[property]);
}
value[dealId] = array2;

Or you can simply use Object.values:

value[dealId] = Object.values(obj);

But note that this does not list inherited properties.

answered Aug 29, 2018 at 8:22

riv

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Comments

Nina Scholz · Accepted Answer · 2018-08-29 08:22:06Z

1

Why not build a new object with a single key and the given array as value?

For the object use a computed property name.

const
    array = [{ a: 'abc', b: 'cd' }, { a: 'abc', b: 'xyz' }, { a: 'abc', b: 'mno' }],
    key = 123,
    object = { [key]: array };

console.log(object);

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

answered Aug 29, 2018 at 8:22

Nina Scholz

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3 Comments

Vikasdeep Singh Over a year ago

but his expected key is without "". Expected is 123 not "123"

Nina Scholz Over a year ago

@VicJordan, the keys of objects are always strings.

Vikasdeep Singh Over a year ago

Yes I know but I think it would be better if we can tell the same to OP i.e. this information in your question. Thanks!

Manasi · Accepted Answer · 2018-08-29 08:24:15Z

0

you need to add into aaray first then create the object

 

const array1 = [{a: 'abc', b: 'cd'}, {a: 'abc', b: 'xyz'}, {a: 'abc', b: 'mno'}];
let obj = array1.reduce(function(result, item, index){
    result[index] = item
  return result;
}, {});

let dealId = 123;
let value = {};
let array2 = [];
for (var property in obj) {
  array2.push(obj[property]);
}
 value[dealId] = array2;
console.log(value);

answered Aug 29, 2018 at 8:24

Manasi

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Comments

Red Devil · Accepted Answer · 2018-08-29 08:25:30Z

0

const array1 = [{a: 'abc', b: 'cd'}, {a: 'abc', b: 'xyz'}, {a: 'abc', 
b: 'mno'}];
let obj = array1.reduce(function(result, item, index){
    result[index] = item
  return result;
}, {});

let dealId = 123;
let value = {};
let array2 = [];
for (var property in obj) {
   array2.push(obj[property]);
}

value[dealId] = array2;

console.log(value)

answered Aug 29, 2018 at 8:25

Red Devil

294 bronze badges

Comments

YarinDekel · Accepted Answer · 2018-08-29 08:29:47Z

0

Assign your new obj property (id) the requested array:



    let arr = [{a: 'abc', b: 'cd'}, {a: 'abc', b: 'xyz'}, {a: 'abc', 
    b: 'mno'}];
    let newObj = {};
    let id = 123;

    newObj[id] = arr;
    console.log(newObj);

answered Aug 29, 2018 at 8:29

YarinDekel

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