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Rename ALBUM_API to MUSIC_API and fix typo #55

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16 changes: 8 additions & 8 deletions book-content/chapters/13-modules-scripts-declaration-files.md
Original file line number Diff line number Diff line change
Expand Up @@ -280,13 +280,13 @@ type Album = {
releaseDate: string;
};

declare const ALBUM_API: {
declare const MUSIC_API: {
getAlbumInfo(upc: string): Promise<Album>;
searchAlbums(query: string): Promise<Album[]>;
};
```

Because we haven't included any imports or exports, this file is treated as a script. This means that the `ALBUM_API` variable is now available globally in our project.
Because we haven't included any imports or exports, this file is treated as a script. This means that the `MUSIC_API` variable is now available globally in our project.

#### Scoping Global Variables To One File

Expand All @@ -301,17 +301,17 @@ type Album = {
releaseDate: string;
};

declare const ALBUM_API: {
declare const MUSIC_API: {
getAlbumInfo(upc: string): Promise<Album>;
searchAlbums(query: string): Promise<Album[]>;
};

export function getAlbumTitle(upc: string) {
return ALBUM_API.getAlbumInfo(upc).then((album) => album.title);
return MUSIC_API.getAlbumInfo(upc).then((album) => album.title);
}
```

Now, `ALBUM_API` is only available in the `musicUtils.ts` file. `declare` defines the value within the scope it's currently in. So, because we're now inside a module (due to the `export` statement), `ALBUM_API` is scoped to this module.
Now, `MUSIC_API` is only available in the `musicUtils.ts` file. `declare` defines the value within the scope it's currently in. So, because we're now inside a module (due to the `export` statement), `MUSIC_API` is scoped to this module.

#### `declare const`, `declare var`, `declare let`, `declare function`

Expand Down Expand Up @@ -343,7 +343,7 @@ type Album = {
// ---cut---
// inside musicUtils.ts
declare global {
declare const ALBUM_API: {
declare const MUSIC_API: {
getAlbumInfo(upc: string): Promise<Album>;
searchAlbums(query: string): Promise<Album[]>;
};
Expand All @@ -356,14 +356,14 @@ This almost works, except for the error. We can't use `declare` inside an ambien
// inside musicUtils.ts

declare global {
const ALBUM_API: {
const MUSIC_API: {
getAlbumInfo(upc: string): Promise<Album>;
searchAlbums(query: string): Promise<Album[]>;
};
}
```

Now the `ALBUM_API` variable has been put into the global scope.
Now the `MUSIC_API` variable has been put into the global scope.

### `declare module`

Expand Down
2 changes: 1 addition & 1 deletion book-content/chapters/16-the-utils-folder.md
Original file line number Diff line number Diff line change
Expand Up @@ -216,7 +216,7 @@ const getFirstElement = <TMember>(arr: TMember[]) => {

Just like generic functions, it's common to prefix your type parameters with `T` to differentiate them from normal types.

Now when we call `getFirstElement`, TypeScript will infer the type of `` based on the argument we pass in:
Now when we call `getFirstElement`, TypeScript will infer the type of `TMember` based on the argument we pass in:

```ts twoslash
const getFirstElement = <TMember>(arr: TMember[]) => {
Expand Down