TypeScript doesn’t support extension methods.

The @x9_extension JSDoc annotation lets you “tag” functions that are meant to be used as extensions methods for a particular type.

This information is later used by the IDE to include these “extension methods” in relevant autocomplete scenarios.

For example:

// string_utils.ts/** * @x9_extension */function shout(str: string) {  return `${str}!`;}

Now every time you trigger autocomplete on a string value, you’ll see shout() listed alongside .toString(), .toUppercase(), etc.

Notes:

• This annotation does not introduce any compile-time behavior. It only affects autocomplete suggestions