turning an array into an object using es6 map

user_102469 0
Viewed 90

I currently have the following data structure:

const bar = [
    {id:1, version:0, name:"test name A"},
    {id:2, version:0, name:"test name B"},
    {id:3, version:0, name:"test name C"}
];

And I need to turn it into this:

const foo = {
    1:{id:1, version:0, name:"test name A"},
    2:{id:2, version:0, name:"test name B"},
    3:{id:3, version:0, name:"test name C"}
};

The piece of code I actually have is this:

for(let i=0;len = bar.length; i< len;i++){
    foo[bar[i].id]= bar[i];
}

I've tried doing

bar.map((element,index)=>{
    const temporal = {[index]:element};
    foo = {...foo, temporal};
});

but I'm lost, any suggestions?

ecmascript-6 arrays javascript
5 Answers

You can use reduce() with Object.assign()

const bar = [
    {id:1, version:0, name:"test name A"},
    {id:2, version:0, name:"test name B"},
    {id:3, version:0, name:"test name C"}
];

var result = bar.reduce((r, e) => Object.assign(r, {[e.id]: e}), {});
console.log(result)

user_46207710

You could use Object.assign with Array#map and spread syntax ...

const
    bar = [{ id: 1, version: 0, name: "test name A" }, { id: 2, version: 0, name: "test name B" }, { id: 3, version: 0, name: "test name C" }],
    object = Object.assign(...bar.map(o => ({ [o.id]: o })));

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

user_14476750

Array.map returns an array, if you wanted to return an object, you could use Array.reduce instead

const bar = [
    {id:1, version:0, name:"test name A"},
    {id:2, version:0, name:"test name B"},
    {id:3, version:0, name:"test name C"}
];

var foo = bar.reduce( (a,b,i) => (a[i+1] = b, a), {});

console.log(foo);

If you just need to reformat the data for sending it to an API, there's no need to create true clones of the objects with Object.assign

user_9650510

You can use reduce, aka fold or inject in general:

const bar = [
    {id:1, version:0, name:"test name A"},
    {id:2, version:0, name:"test name B"},
    {id:3, version:0, name:"test name C"}
];

bar.reduce((obj, e, i) => { obj[e.id] = e; return obj}, {});
user_17400790

Another way could be to use forEach which iterates over the array, but doesn't return an array as map does:

let foo = {};
bar.forEach((el, idx) => foo[idx+1] = el)
user_78749310
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