JSON.stringify should have type string | undefined

[markfields]

Bug Report

🔎 Search Terms

stringify, JSON.stringify undefined

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about stringify

⏯ Playground Link

Playground link with relevant code

💻 Code

// hover over 'x', it's typed as string.
const x = JSON.stringify(undefined);
console.log(typeof x)  // outputs "undefined"

🙁 Actual behavior

Return type of JSON.stringify is string but it can return undefined

🙂 Expected behavior

Return type should reflect actual set of values that could be returned: string | undefined

[IllusionMH]

Duplicate of #18879

Ton of duplicates can be found with search for JSON.stringify undefined

[markfields]

Sure enough! I adjusted my query to include quotes and found the one you linked right away. Closing.