Sample of call and apply methods

call-apply.js

// Person
var Person = function( firstName, lastName ) {
      
    // Asign attributes    
    this.first_name = firstName;
    this.last_name = lastName;
    
    // Say name method
    this.sayName = function() {
       console.log( "%s %s", this.firstName, this.lastName );
    }
    
};

// Person 1
var jane = new Person( "Jane", "Smith" );
jane.sayName(); // Jane Smith

// Person 2
var peter = new Person( "Peter", "Doe" );
petter.sayName(); // Petter Doe

// Using call to invoke method with the passed context
jane.sayName.call( petter ); // "Petter Doe"

// now on person 2
petter.sayName.call( jane ); // Jane Doe