CODEWITHSUNDEEP
reactjstypescript
Naor
Naor

Reputation: 24093

Remove concerns from typescript

In typescript with react, I have the following situation:

    if (isEdit && !itemToEdit) {
        return <StepSpinner />;
    }
    ...
    ...
    return <MyComponent  itemId={itemToEdit.id} />;

itemToEdit definition is itemToEdit?: Item; (optional). Typescript gives me an error: Object is possibly 'undefined'.
If I change the condition to if (!itemToEdit) {, the error disappear.

How can I tell typescript "trust me, this is not undefined"?
In my real world code I have many usages of itemToEdit and I don't want to use casting because those are points of failure.
Is there any solution to such case?

Upvotes: 1

Views: 52

Answers (1)

Martin
Martin

Reputation: 16302

If you are sure that itemToEdit cannot be undefined, you can use TypeScript's non-null assertion operator.

itemToEdit!.id

This simply tells TypeScript, trust me, it's fine.

Upvotes: 2

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