How to convert a Set to JSON in JavaScript

Convert a Set to JSON in JavaScript #

To convert a Set to JSON, convert the Set to an array and pass the result to the JSON.stringify() method, e.g. JSON.stringify(Array.from(set)). The JSON.stringify method converts the passed in value to a JSON string and returns the result.

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const set1 = new Set(['a', 'b', 'c']);

// ✅ Using Array.from
const json1 = JSON.stringify(Array.from(set1));
console.log(json1); // 👉️ '["a", "b", "c"]'

// ✅ Using spread syntax (...)
const json2 = JSON.stringify([...set1]);
console.log(json2); // 👉️ '["a", "b", "c"]'

We used the Array.from method to convert a Set to an array.

The method takes an iterable object and converts it to an array.

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const set1 = new Set(['a', 'b', 'c']);

console.log(Array.from(set1)); // 👉️ ['a', 'b', 'c']

The last step is to use the JSON.stringify method to convert the array to a JSON string.

An alternative to using the Array.from method is to use the spread syntax (...).

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const set1 = new Set(['a', 'b', 'c']);

const json2 = JSON.stringify([...set1]);
console.log(json2); // 👉️ '["a", "b", "c"]'

In this example, we used the spread syntax (...) to unpack the values from the Set into an array.

If you need to convert the JSON string to a Set, you have to:

1. use the JSON.parse() method to parse the JSON string to an array.
2. pass the array to the Set() constructor

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const set1 = new Set(['a', 'b', 'c']);

const json1 = JSON.stringify(Array.from(set1));
console.log(json1); // 👉️ '["a", "b", "c"]'

// ✅ Parse back to Set
const parsed = new Set(JSON.parse(json1));
console.log(parsed); // 👉️ {'a', 'b', 'c'}

The Set constructor takes an iterable, such as an array, as a parameter, so we can pass it the result from calling the JSON.parse method.

Further Reading #

• Convert an Array of Objects to a Map in JavaScript
• Convert a Set to a String in JavaScript