How to find id in array object then edit and delete a object in oop javascript?

Question

I coding demo student management . But have problem below, please help me resolve them.

The requirement

• Manage student : add, edit, remove
• Using console building data table. The table contain fiedls: id Name Age Point
• Using console call function
• List all student have point > = 5;

This is my code:

---

//
function Student(id, name, age, point) {
  this.id = id;
  this.name = name;
  this.age = age;
  this.point = point;
}

Student.prototype = {
  setId: function (value) {
    this.id = value;
  },

  getId: function () {
    return this.id;
  },

  setName: function (value) {
    this.name = value;
  },

  getName: function () {
    return this.name;
  },

  setAge: function (value) {
    this.age = value;
  },

  getAge: function () {
    return this.age;
  },

  setPoint: function (value) {
    this.point = value;
  },

  getPoint: function () {
    return this.point;
  },

};

function StudentController(student) {
  this.listStudent = [];
  this.id = 1;
}

StudentController.prototype = {
  addNew: function (name, age, point) {
    var student = new Student(this.id, name, age, point);
    this.listStudent.push(student);
    this.id += 1;
    return student;
  },

---

This is function find id . But it always return last id in array object.

  findId: function (id) {
    var student = null;
    for (var i = 0; i < this.listStudent.length; i++) {
      if (id = this.listStudent[i].getId()) {
        student = this.listStudent[i];
      }
    }

    return student;
  },

---

This is function edit student. But it can't getId from function findId();

  editStudent: function (student) {
    var oldStudent = this.findId(student.getId());
    console.log('oldStudent', oldStudent);
    for (var x = 0; x < this.listStudent.length; x++) {
      if (oldStudent = this.listStudent[x].getId()) {
        this.listStudent[x] = student;
      }
    }
  },

---

This function same too editStudent() function.

  deleteStudent: function (student) {
    var crrentStudent = this.findId(student.getId());
    for (var y = 0; y < this.listStudent.length; y++) {
      if (crrentStudent.getId() === this.listStudent[y]) {
        this.listStudent.splice(y, 1);
      }
    }
  },

---

This this function sort point of student > = 5. But look like not working :(

  // find point student > = 5
  findByPoint: function (point) {
    var point = '';
    for (var i = 0; i < this.listStudent.length; i++) {
      if (this.listStudent[i].getPoint() >= point) {
        return point;
      }
    }
  },

  showStudent: function () {
    console.table(this.listStudent);
  },
};

var studentController = new StudentController();
studentController.addNew("Hanh", 20, 8);
studentController.findId(1);
studentController.editStudent();
studentController.deleteStudent();

---

Please help me resolve and explanation. Thank you so much !!

Answer 1

The problem is pretty straight forward, for a comparison operator you need == in if condition , = is for assignment and adding

Change findId() function

findId: function (id) {
    var student = null;
    for (var i = 0; i < this.listStudent.length; i++) {
      if (id == this.listStudent[i].getId()) {    // change here
        student = this.listStudent[i];
      }
    }

    return student;
  },

and in editStudent function

editStudent: function (student) {
    var oldStudent = this.findId(student.getId());
    console.log('oldStudent', oldStudent);
    for (var x = 0; x < this.listStudent.length; x++) {
      if (oldStudent == this.listStudent[x].getId()) {    //change here 
        this.listStudent[x] = student;
      }
    }
  },