How can I override a method in a prototype chain without affecting other instances in JavaScript?

<!-- BEGIN COPY / PASTE -->
        function Animal(name) {
            this.name = name;
        }

        Animal.prototype.speak = function() {
            return `${this.name} makes a noise.`;
        };

        const dog = new Animal('Dog');
        const cat = new Animal('Cat');

        // Override the speak method for the dog instance only
        dog.speak = function() {
            return `${this.name} barks.`;
        };

        console.log(dog.speak()); // "Dog barks."
        console.log(cat.speak()); // "Cat makes a noise."
        <!-- END COPY / PASTE -->