add the old snippet md files

old_snippets/re-export-js-fn.en.md

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+---
+title: "re-export javascript function"
+date: 2021-10-05T08:45:34+02:00
+draft: false
+snippet_types:
+- js
+---
+
+When splitting logic into files in JavaScript it sometimes happens you have a folder of files; say
+for a single domain like Google analytics tracking. There comes a time in another part of the code
+where you need to import some functions and types from this GATracking folder but you may not want
+to dig into which file in the folder that function is. Re-exporting allows us to keep the API of the
+GATracking logic consise and allow the rest of the program to not worry about how exactly the files
+are structured. Example:
+
+src/client/hooks/GATracking/index.tsx
+```ts
+export { default as TrackingAction } from './actions';
+export const track = (action: TrackingAction) =>
+...
+```
+
+Then somewhere else:
+src/client/components/GoButton/index.tsx
+
+```ts
+import {TrackingAction, track} from '../hooks/GATracking';
+...
+```
+
+source: https://stackoverflow.com/questions/34576276/re-export-a-default-export