Based on crypto.subtle.exportKey("spki", cryptoKey) I want to convert the returned ArrayBuffer into a string so I can turn it into a base64 string. Based on the documentation I tried

const bufferAsString = String.fromCharCode.apply(null, new Uint8Array(buffer));

but TypeScript tells me

TS2345: Argument of type 'Uint8Array' is not assignable to parameter of type 'number[]'.

How can I fix the type errors?

Based on crypto.subtle.exportKey("spki", cryptoKey) I want to convert the returned ArrayBuffer into a string so I can turn it into a base64 string. Based on the documentation I tried

const bufferAsString = String.fromCharCode.apply(null, new Uint8Array(buffer));

but TypeScript tells me

TS2345: Argument of type 'Uint8Array' is not assignable to parameter of type 'number[]'.

How can I fix the type errors?

• javascript
• typescript

• See stackoverflow.com/questions/53603770/… – James Commented Apr 7, 2023 at 19:21
• Side note: <github.com/tc39/proposal-arraybuffer-base64>, if adopted, will likely make this solution obsolete. Though of course, it’d need to be polyfilled on older environments… – dumbass Commented Apr 7, 2023 at 19:55

2 Answers 2

Use parameters spread when you call the function instead of using apply (playground):

String.fromCharCode(...new Uint8Array(buf));

You could use spread syntax or Array.from to convert the Uint8Array to a regular array.

String.fromCharCode.apply(null, [...new Uint8Array(buffer)]);