2_js advanced exam

function solveClasses() {

    class Developer {

        constructor(firstName, lastName) {

            this.firstName = firstName;

            this.lastName = lastName;

            this.baseSalary = 1000;

            this.tasks = [];

            this.experience = 0;

        }



        addTask(id, taskName, priority) {

            if (priority === 'high') {

                this.tasks.unshift({ id, taskName, priority });

            }

            else {

                this.tasks.push({ id, taskName, priority });

            }



            return `Task id ${id}, with ${priority} priority, has been added.`;

        }



        doTask() {

            let task;

            let index = 0;



            for (let i = this.tasks.length; i > 0; i++) {

                if (this.tasks[i].priority === 'high') {

                    task = this.tasks[i];

                    break;

                }

            }



            index = this.tasks.indexOf(task);



            this.tasks = this.tasks.splice(index, 1);



            return `${task.taskName}, you have finished all your tasks. You can rest now.`;

        }



        getSalary() {

            return `${this.firstName} ${this.lastName} has a salary of: ${this.baseSalary}`;

        }



        reviewTasks() {

            let result = [];



            result.push('Tasks, that need to be completed:');



            for (let task of this.tasks) {

                result.push(`${task.id}: ${task.taskName} - ${task.priority}`);

            }



            return result.join('\n');

        }

    }



    class Junior extends Developer {

        constructor(firstName, lastName, bonus, experience) {

            super(firstName, lastName);

            this.baseSalary = this.baseSalary + bonus;

            this.tasks = [];

            this.experience = experience;

        }



        learn(years) {

            this.experience += Number(years);

        }

    }



    class Senior extends Developer {

        constructor(firstName, lastName, bonus, experience) {

            super(firstName, lastName);

            this.baseSalary = this.baseSalary + bonus;

            this.experience = Number(experience) + 5;

        }



        changeTaskPriority(taskId) {

            let task = this.tasks.find(x => x.id === taskId);

            let index = this.tasks.indexOf(task);



            this.tasks = this.tasks.splice(index, 1);



            if (task.priority === 'high') {

                task.priority = 'low';

                this.tasks.push(task);

            }

            else {

                task.priority = 'high';

                this.tasks.unshift(task);

            }



            return task;

        }

    }



    return {

        Developer,

        Junior,

        Senior

    }

}