JSON.stringify's Second Parameter Most Developers Skip
2025-04-01
Beyond JSON.stringify(obj)—replacer controls which keys export; space controls indentation. Handy for logs, mocks, and storage.
replacer array = whitelist
Pass ['id','name'] to emit only those keys at top level.
JSON.stringify(user, ["id", "name"]);replacer function
Return undefined to omit; redact passwords; custom Date formatting.
JSON.stringify(obj, (k, v) => k === "password" ? undefined : v);space
Third arg 2 or '\t' for pretty JSON; omit for compact logs.
toJSON
Objects can define toJSON(); Date uses ISO strings by default.