使用es6 map将数组转换为对象

Question

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?

Answer 1

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) 

Answer 2

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; } 

Answer 3

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

Answer 4

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}, {});

Answer 5

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)