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JavaScript - convert array to object with values as keys

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Created by:

a_horse

538

In this article, we would like to show you how to convert array to object with array values as keys working with JavaScript.

Quick solution:

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const array = ['a', 'b', 'c'];
const object = array.reduce((object, item) => (object[item] = item, object), {});
​
console.log(JSON.stringify(object, null, 4));

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or:

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const array = ['a', 'b', 'c'];
const result = array.reduce((object, item) => ({...object, [item]: item}), {});
​
console.log(JSON.stringify(result, null, 4));

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Warning: the solution based on spread operator is not recommended because of bad time performance.

Practical examples

Edit

In this examples, we create a reusable function that converts the array to object with the array values as keys using reduce() method.

1. Assigning property based example

Edit

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const toObject = (array) => {
    return array.reduce((object, item) => (object[item] = item, object), {});
};
​
​
// Usage example:
​
const array = ['a', 'b', 'c'];
const object = toObject(array); 
​
console.log(JSON.stringify(object, null, 4));

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2. Spread operator based example

Edit

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const toObject = (array) => {
    return array.reduce((object, item) => ({ ...object, [item]: item }), {});
};
​
​
// Usage example:
​
const array = ['a', 'b', 'c'];
const object = toObject(array); 
​
console.log(JSON.stringify(object, null, 4));