switch.js

String color = 'Y'; 
//Expression should be any of the allowable type value
    switch on color {
        when 'V' {
            System.debug('Violet');
        }
        
        when 'I' {
            System.debug('Indigo');
        }
        //Multiple values given as comma seperated
        when 'B','G' {
            System.debug('Blue or Green');
        }
        
        when 'Y','O','R' {
            System.debug('Yellow or Orange or Red');
        }
            
        when null {
            System.debug('Bad Value');
        }
       
        when else {
            System.debug('Not in spectrum');
        }
          
    }