DefineMap.toStream( propAndOrEvent[,event] )

Creates a stream that gets updated whenever the property value changes or event is triggered.

import DefineMap from "can-define/map/map";
import canStream from "can-stream-kefir";
import canDefineStream from "can-define-stream";

const Person = DefineMap.extend( {
    name: "string",
    lastValidName: {
        stream: function() {
            return this.toStream( ".name" ).filter( function( name ) { // using propName
                return name.indexOf( " " ) >= 0;
            } );
        }
    }
} );

canDefineStream( canStream )( Person );

const me = new Person( { name: "James" } );

me.on( "lastValidName", function( lastValid ) {} );

me.name = "JamesAtherton"; //lastValidName -> undefined
me.name = "James Atherton"; //lastValidName -> James Atherton