observation.value

The following creates a fullName observation that derives its values from the person observable. The value of the observation is read with fullName.value:

import Observation from "can-observation";
import observe from "can-observe";

const person = observe( { first: "Grace", last: "Hopper" } );

const fullName = new Observation( function() {
    return person.first + " " + person.last;
} );

fullName.value; //-> "Grace Hopper";