Triple-slash directives in Typescript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a triple-slash directive in TypeScript?

A triple-slash directive is a single-line comment starting with /// that provides compiler instructions, like referencing other files or types.

beginner

How do you reference another file using a triple-slash directive?

You use /// <reference path="filename.ts" /> at the top of your TypeScript file to tell the compiler to include that file.

intermediate

What is the purpose of /// <reference types="..." /> directive?

It tells the compiler to include type declarations from a package, usually from node_modules/@types, so you get type info for libraries.

beginner

Where should triple-slash directives be placed in a TypeScript file?

They must be placed at the very top of the file, before any other code or import statements.

intermediate

Can triple-slash directives affect module resolution in TypeScript?

Yes, they can guide the compiler to find files or types that are not automatically discovered, helping with module resolution.

What does the triple-slash directive /// <reference path="utils.ts" /> do?

A Comments out the utils.ts file

B Imports a module named utils

C Declares a variable named utils

D Includes the file utils.ts for compilation

The directive tells the compiler to include the referenced file utils.ts during compilation.

Where must triple-slash directives appear in a TypeScript file?

A At the very top before any code

B At the bottom of the file

C Anywhere in the file

D Inside functions only

Triple-slash directives must be at the top of the file before any other code or imports.

Which triple-slash directive is used to include type declarations from a package?

A /// <reference path="..." />

B /// <include types="..." />

C /// <reference types="..." />

D /// <import types="..." />

The /// <reference types="..." /> directive includes type declarations from packages.

What symbol starts a triple-slash directive in TypeScript?

A //

B ///

C /*

D <!--

Triple-slash directives start with three slashes: ///.

Can triple-slash directives be used to affect module resolution?

A Yes, they help the compiler find files or types

B No, they only add comments

C Yes, but only for JavaScript files

D No, they are deprecated

Triple-slash directives guide the compiler to find files or types, affecting module resolution.

Explain what triple-slash directives are and how they are used in TypeScript.

Think about how TypeScript knows about other files or type info.

Describe the difference between /// <reference path="..." /> and /// <reference types="..." /> directives.

One is for files, the other is for type packages.