How can I difference id (number) and email (string) in Javascript?

I have API and some of them return to only email and some return only id. For example:

user1 value: [e-mail]

user2 value: 1212391361783212

I need that if I have input and wanna give value if the value is email. If the value is id, the input value must be null

<input value={???}/>

Answer

Your code sample is incomplete but what you’re trying to do should look something like this. Rather than assuming any non-numerical response is a valid email, which can break in the future as the API changes, be explicit about what you’re looking for as below.

// Assume you're comfortable using a relatively loose pattern to match an email i.e. no overly strict formatting rules
const mailPattern = /^[a-zA-Z0-9.!#$%&’*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:.[a-zA-Z0-9-]+)*$/
// Assume response is in scope and contains the API response with the email or id deserialized from the body
const value = mailPattern.test(response) ? value : null