When do I need a triple slash reference?

Question

When Anders Hejlsberg is talking about external modules around 35:00 in the following video...

Anders Hejlsberg: Introducing TypeScript

... why does the file server.ts require a triple slash reference to node.d.ts where as hello.ts doesn't require a similar reference to server.ts?

In particular in hello.ts he mentions that intellisense is present plus he gets to use the exported item from server.ts. So what more could the triple slash reference add?

score 26 · Accepted Answer · edited Jun 07 '20 at 16:20

You need a triple slash reference in two scenarios:

When you are referencing JavaScript type definitions e.g. definitions for node, jQuery, etc. for a great collection see : https://github.com/DefinitelyTyped/DefinitelyTyped
When we want to compile using --out you can reference your files using /// <reference.

You need a import/require combo when using external modules i.e. amd/commonjs. If you don't know what these mean (amd/commonjs are javascript terms, not specific to typescript) you don't have to care. Just use /// <reference and compile with --out.

PS: I have a video tutorial on internal vs. external modules: TypeScript Modules Demystified : Internal, AMD with RequireJS, CommonJS with NodeJS

Update:

Please use tsconfig.json for new projects instead of reference comments : https://basarat.gitbook.io/typescript/project/compilation-context

@basarat, agree with DarkNeuron, your link is simply mystifying to me as to how it applies to this question. — Kirk Woll, Feb 17 '17 at 15:08
I guess he's talking about adding the file to the `"compilerOptions": {"types": [], }` property of `tsconfig.json`. — Juangui Jordán, Jan 21 '18 at 23:48

When do I need a triple slash reference?

1 Answers1

Update:

Linked