SOLVED
SOURCE: https://codeolives.com/2019/09/18/vs-code-why-javascript-intellisense-is-not-working/
Somehow my buitin extesion "TypeScript and JavaScript Language Features" was disabled, to autocompletion works this extension had to be enabled
Go to:
extensions sidebar tab > Filter icon > Built-in
Search for "typescript" and enable "TypeScript and JavaScript Language Features"
This part isnt in the source i linked above, but you need it too:
Make sure you have this on your settings.json file:
"[javascript]": {
"editor.defaultFormatter": "vscode.typescript-language-features",
},
