Implemented by @mozilla.org/uuid-generator; as a service:

var uuidGenerator = Components.classes["@mozilla.org/uuid-generator;1"]
                    .getService(Components.interfaces.nsIUUIDGenerator);

Method overview

Methods

generateUUID()

Obtains a new UUID using appropriate platform-specific methods to obtain a nsID that can be considered to be globally unique.

nsIDPtr generateUUID();

Parameters

None.

Return value

This method returns a nsIDPtr containing a unique ID.

Exceptions thrown

NS_ERROR_FAILURE

If a UUID cannot be generated (for example if an underlying source of randomness is not available)

Obtain a new UUID like the generateUUID() method, but place it in the provided nsID pointer instead of allocating a new nsID.

void generateUUIDInPlace(
  in nsNonConstIDPtr id
);

Parameters

id

An existing nsID pointer where the UUID will be stored.

Exceptions thrown

NS_ERROR_FAILURE

If a UUID cannot be generated (for example if an underlying source of randomness is not available)

Example

Generating a UUID

var uuidGenerator = Components.classes["@mozilla.org/uuid-generator;1"]
                    .getService(Components.interfaces.nsIUUIDGenerator);
var uuid = uuidGenerator.generateUUID();
var uuidString = uuid.toString();