Trailing commas (sometimes called "final commas") can be useful when adding new elements, parameters, or properties to JavaScript code. If you want to add a new property, you can add a new line without modifying the previously last line if that line already uses a trailing comma. This makes version-control Diffs cleaner and editing code might be less troublesome....This makes version-control diffs cleaner and editing code might...editing and reviewing the diff. diff [ "foo", + "baz", "bar",...