One-liner for converting an array into an object

Question

One-liner for converting an array into an object

Is there a more concise method to convert all array indices and values into an object than the following:

arr = ["one","two","three"];
var rv = {};
for (var i = 0; i < arr.length; i++)
    rv[i] = arr[i];

I understand that you can iterate through the array and manually add each element to a new object, but I strongly dislike adding extra loops to my code whenever I need to make this switch, especially when giving solutions here on SO (and creating a function is not an option, as it would only add unnecessary bulk to an answer).

PS: Feel free to share any unconventional or frowned-upon approaches, since I find JavaScript hacks quite intriguing. :)

javascript arrays javascript-objects

Answer 1

Answer №1

Is there a quick method to convert array indices and values into key value pairs in an object?

Actually, arrays in JavaScript are essentially objects with properties corresponding to the array indexes. They don't adhere strictly to the traditional definition of arrays in computer science. You can read more about this here.

In many cases, you may not even need to perform this conversion. However, if you find yourself needing to do so, there isn't a direct shortcut. It will involve some form of looping, either visibly in your code or hidden within a function. Your approach to achieving this transformation is likely as efficient as any other.

Answer 2

Is there a quick method to convert array indices and values into key value pairs in an object?

Actually, arrays in JavaScript are essentially objects with properties corresponding to the array indexes. They don't adhere strictly to the traditional definition of arrays in computer science. You can read more about this here.

In many cases, you may not even need to perform this conversion. However, if you find yourself needing to do so, there isn't a direct shortcut. It will involve some form of looping, either visibly in your code or hidden within a function. Your approach to achieving this transformation is likely as efficient as any other.

Answer 3

Answer №2

Below is a clever trick:

Assigning the prototype of myArray to Object.prototype

Answer 4

Below is a clever trick:

Assigning the prototype of myArray to Object.prototype

Answer 5

Answer №3

Just a reminder, arrays are considered objects as well: typeof [] === 'object'

Here's an alternative approach:

function convertToArrayToObjects(arr) {
    return arr.reduce({}, function (previous, element, index) {
        previous[index] = element;
        return previous;
    });
}

This solution may not be more efficient than yours, but it eliminates the need to declare index. To improve performance, consider moving the anonymous function outside of convertToArrayToObjects.

Answer 6

Just a reminder, arrays are considered objects as well: typeof [] === 'object'

Here's an alternative approach:

function convertToArrayToObjects(arr) {
    return arr.reduce({}, function (previous, element, index) {
        previous[index] = element;
        return previous;
    });
}

This solution may not be more efficient than yours, but it eliminates the need to declare index. To improve performance, consider moving the anonymous function outside of convertToArrayToObjects.

One-liner for converting an array into an object

Answer №1

Answer №2

Answer №3

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