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parseJSON

For types other than strings, the value is returned as-is. For strings, if it is a valid JSON Format, the string is converted using JSON.parse and the resulting value is returned. If it is not a valid JSON Format, an error is thrown.

In TypeScript, JSON.parse only accepts strings as arguments. This function allows it to be applied in a wider variety of cases.


Code​

🔗 View source code


Interface​

typescript
export function parseJSON<T = unknown>(value: string): T;

export function parseJSON<T>(value: T): T;

Usage​

Parsing a String Value​

When the value type is string, a precise generic (T) type must be provided to get an accurate return type. If no generic (T) type is provided, unknown is used as the return type, since JSON.parse can produce any type.

typescript
import { parseJSON } from '@modern-kit/utils';

type NormalObject = { a: 1, b: 2 }

const number1 = parseJSON("123");
// value: 123
// type: unknown

const number2 = parseJSON<number>("123");
// value: 123
// type: number

const str = parseJSON<string>('"123"');
// value: "123"
// type: string

const normalObject = parseJSON<NormalObject>(`{ "a": 1, "b": 2 }`);
// value: { a: 1, b: 2 }
// type: NormalObject

Handling Non-String Types​

When the value type is not string, the value is returned as-is, so the return type matches the value's type even without specifying a generic (T) type.

typescript
import { parseJSON } from '@modern-kit/utils';

type NormalObject = { a: 1, b: 2 }

const number = parseJSON(123);
// value: 123
// type: number

const normalObject = parseJSON({ a: 1, b: 1});
// value: { a: 1, b: 1 }
// type: { a: number; b: number }

const str = parseJSON<number>([1, 2, 3]);
// TypeError: Argument of type 'number[]' is not assignable to parameter of type 'number'.