JSON.stringify can return undefined

[farnoy]

⚙ Compilation target

ES2018

⚙ Library

es2018

Missing / Incorrect Definition

JSON.stringify always returns string

TypeScript/src/lib/es5.d.ts

Line 1151 in 01a874a

stringify(value: any, replacer?: (this: any, key: string, value: any) => any, space?: string | number): string;

But JSON.stringify(undefined) returns undefined

Sample Code

const whatever: string | undefined = `JSON.stringify(undefined)`;

Documentation Link

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#return_value

[jcalz]

Duplicate #18879

See #18879 (comment)