Best practices for using trailing commas in JavaScript

Trailing commas, introduced in JavaScript with array literals and later extended to objects and various language constructs like parameter lists and function calls with ES2017, can simplify code maintenance and produce cleaner version control diffs by reducing the need to modify preceding lines when adding new elements. While trailing commas are encouraged by some style guides and can prevent syntax errors when reordering or expanding lists, they are not permissible in JSON objects and will cause syntax errors if used incorrectly in function declarations or after the rest parameter in destructuring assignments. The article emphasizes cautious usage, advising against using trailing commas with the rest parameter syntax and noting that their improper use can lead to unexpected errors.