How to handle a return type Maybe<unknown>-CodePudding

Iam using typescript and iam trying to get the accounts from the current user like its showed on the metamask official documentation Metamask Doc:

const accounts = await window.ethereum.request({
                  method: "eth_accounts",
                });

The call to the request function returns a result with the Maybe<unknown> type.

Then iam trying to access the first element of accounts like this because its supposed to be an array of string :

accounts[0]

But i have the following errors:

Object is possibly 'null' or 'undefined'.ts(2533)

Element implicitly has an 'any' type because expression of type '0' can't be used to index type 'Partial<unknown>'.
  Property '0' does not exist on type 'Partial<unknown>'.ts(7053)

So, how can i manage to handle this situation? I need to properly get the return of the request function and make typescript accept it as an array of string.

Thanks.

CodePudding user response：

The errors indicate that the returned value from the request might be null, undefined or even not-an-array value. So you have to check those cases before accessing its value.

const accounts = await window.ethereum.request({
  method: "eth_accounts",
}); 
if (accounts && Array.isArray(accounts)) {
  // Here you can access accounts[0]
} else {
  // Handle errors here if accounts is not valid. 
}