Ambient declarations on Declaration files page has erroneous code example https://basarat.gitbook.io/typescript/type-system/intro/d.ts

Tutorial Documentation: https://basarat.gitbook.io/typescript/type-system/intro/d.ts

> You can tell TypeScript that you are trying to describe code that exists elsewhere (e.g. written in JavaScript/CoffeeScript/The runtime environment like the browser or Node.js) using the declare keyword. As a quick example:

> foo = 123; // Error: `foo` is not defined
vs.

> declare var foo: any;
foo = 123; // allowed

Here `foo = 123;` is not allowed in javascript at all, because of the reference error. In Typescript, you can't have `foo = 123` in the declaration file `.d.ts`; it is supposed to have only type declarations.

`foo = 123;` in a `.ts` file along with `declare var foo: any;` in the `.d.ts` file will cause Typescript to skip the reference error.

Open the tutorial documentation at https://basarat.gitbook.io/typescript/type-system/intro/d.ts and review the ambient declaration example against the issue’s explanation of .d.ts files. Correct the erroneous code example so it distinguishes declaration-file syntax from executable TypeScript, then verify the rendered page and its surrounding wording.

Written by the indexing model from the issue text.