CODEWITHSUNDEEP
javascriptflowtype
user578895
user578895

Reputation:

flow: Simpler way to annotate `type | typeof undefined`?

I constantly run into the same issue with flow: I annotate something as ?type and forget that that accepts null so when I do something like this:

function foo(data: string = '') {}
function bar(data: ?string) { foo(data); }

flow yells at me because foo(null) doesn't resolve data to a string, but foo(undefined) does. So is there a simpler way to write this:

function bar(data: string|typeof undefined) {

Or am I doing something fundamentally wrong?

Upvotes: 0

Views: 408

Answers (1)

Noitidart
Noitidart

Reputation: 37338

typeof undefined is void in flow.

So what about:

function bar(data: string | void | null) {

or 

function bar(data?: string | null) {

Upvotes: 2

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