string

Lowercase string is a primitive data type in JavaScript.

Strings created with this type are not objects, but JavaScript automatically wraps them with a String object (this is called "boxing").

let imAString = "hello";
console.log(typeof imAString); // "string"

String

Uppercase String is a constructor function that creates String objects, an object wrapper around a string primitive.

When you use the String constructor with new, you get a String object rather than a primitive string

String objects are not necessary unless you need to use them as objects explicitly.

let imAStringObject = new String("hello");
console.log(typeof imAStringObject); // "object"

Differences

When to use string/String?

Use string (primitive) in almost all cases. It is more efficient, simpler, and JavaScript automatically provides methods when needed.

Use String (object) only when you specifically need an object with additional properties or when you want to use instanceof checks, though this is rare in practice.

That's it! Thank you for reading this far. Till next time!