isEmail
function isEmail(email: unknown): email is string;
The address is split at a single @: the domain is checked the way isValidDomain checks one, and the local part must be non-empty and free of spaces. It is a format check, not proof that the mailbox exists.
isX and nonX answer a question and never interrupt control flow; requireX and requireNonX hand the value back or throw. The scheme is explained in Validation conventions.
Parameters
Parameter | Type | Description |
|---|---|---|
|
| The value to check, which could be of any type. |
Returns
boolean — true when the value is an email address; otherwise false.
In TypeScript the guard narrows email to string inside the branch.
Examples
What passes and what does not
isEmail("user@example.com"); // => true
isEmail("first.last@sub.example.co.uk"); // => true
isEmail("user@@example.com"); // => false
isEmail("user@"); // => false
isEmail("example.com"); // => false
isEmail(""); // => false
See also
Source
23 September 2026
This documentation was generated with AI (Claude) from the library's source code.