You can wrap your code like this to have multiline comments in TypeScript:
/*your code here*/
Example:
/*
This is how you add multiline comments in TypeScript.
This is how you add multiline comments in TypeScript.
This is how you add multiline comments in TypeScript.
This is how you add multiline comments in TypeScript.
This is how you add multiline comments in TypeScript.
This is how you add multiline comments in TypeScript.
*/