Question 341150 in Javascript Question posted in
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Javascript – use a value instead of an index in array object

I can’t seem to format my array that is being saved to localStorage.
Can you change the index value of an array?
I have an array object like this:

const myArray = [{id: 41, name: "x"}, {id: 42, name: "y"}]

But I want to make it like this:

const myArray = [ 41: {id:41, name:"x" }, 42: {id:41, name:"y" }}

So the id of the object becomes the index of the array

If that is not possible then like this should be fine:

const myArray = [ {41: {id:41, name:"x"} }, {42: {id:41, name:"y"}}]

So basically the id of the object becomes either the index or a container object for that object.

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2

Answers


  1. 0

    You can achieve this by transforming your array into an object where the keys are the IDs and the values are the corresponding objects. Here’s how you can do it:

    const myArray = [{id: 41, name: "x"}, {id: 42, name: "y"}];

// Convert the array into an object
const transformedArray = myArray.reduce((acc, obj) => {
    acc[obj.id] = obj;
    return acc;
}, {});

console.log(transformedArray);

    This will give you the desired result where the IDs are the keys of the object:

    {
  41: {id: 41, name: "x"},
  42: {id: 42, name: "y"}
}

    If you want to wrap each object with its ID, you can use a slightly different approach:

    const transformedArray = myArray.reduce((acc, obj) => {
    acc.push({[obj.id]: obj});
    return acc;
}, []);

console.log(transformedArray);

    This will give you the array where each object is wrapped with its ID:

    [
  {41: {id: 41, name: "x"}},
  {42: {id: 42, name: "y"}}
]
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  2. 0

    You cannot directly change the key of an element in an array to a specific value like an object’s property. Butyou can create an object where the keys are the IDs and the values are the corresponding objects.

    const myArray = [{id: 41, name: "x"}, {id: 42, name: "y"}];
const myObject = {};

// Convert array to object
myArray.forEach(item => {
    myObject[item.id] = item;
});

// Now myObject will look like:
// { 41: {id:41, name:"x"}, 42: {id:42, name:"y"} }

// If you still need it as an array of objects with IDs as keys:
const newArray = Object.keys(myObject).map(key => ({ [key]: myObject[key] }));

// Now newArray will look like:
// [ {41: {id:41, name:"x"} }, {42: {id:42, name:"y"}} ]
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