When using [[string literal types]], its common to run into the following error:
Type 'string' is not assignable to type
Usually the code looks something like this:
type EmailStatus = 'draft' | 'read' | 'unread'; // 👇️ status has type `string` let status = 'draft'; status = 'read'; // ⛔️ Error: Type 'string' is not // assignable to type 'EmailStatus'.ts(2322) const current: EmailStatus = status;
This is because status is using the broader type of string, rather than the narrower type of EmailStatus.
One possible solution is to cast the value to the type:
let status = 'draft' as EmailStatus;
The other solution is to narrow the type with a [[const assertion]]:
let status = 'draft' as const;