Update JSON.stringify undefined cases

[codersjj]

Description

• Reorder the examples to align with the first sentence’s claim.
• Add an example demonstrating JSON.stringify() returning undefined for "pure" value Symbol.

Motivation

The documentation states that "undefined, Function, and Symbol values are not valid JSON values.", but lacked a concrete example for Symbol. This change adds JSON.stringify(Symbol()) to explicitly show the behavior.

JSON.stringify(undefined)      // → undefined
JSON.stringify(() => {})       // → undefined
JSON.stringify(Symbol())       // → undefined

Additional details

Related issues and pull requests

[github-actions]

Preview URLs

• /en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify

[Josh-Cena]

Thanks, but the goal of these quick examples is never to be exhaustive. With two examples it should be trivial to figure out the third oneself.