Check if value of an object of certain class has been altered in JavaScript and update another value based on it?

To check this, use the concept of getter, i.e. the get property. Following is the code −

Example

class Student{
   constructor(studentMarks1, studentMarks2){
      this.studentMarks1 = studentMarks1
      this.studentMarks2 = studentMarks2
      var alteredValue = this;
      this.getValues = {
         get studentMarks1() {
            return alteredValue.studentMarks1
         },
         get studentMarks2() {
            return alteredValue.studentMarks2
         }
      }
   }
}
var johnSmith = new Student(78,79)
console.log("Before incrementing the result is=")
console.log("StudentMarks1="+johnSmith.studentMarks1,"StudentMarks2="+johnSmith.studentMarks2);
johnSmith.studentMarks2+=10;
console.log("After incrementing the value 10 in the studentMarks2, the result is as follows=")
console.log("StudentMarks1="+johnSmith.studentMarks1,
"StudentMarks2="+johnSmith.getValues.studentMarks2);

To run the above program, you need to use the following command −

node fileName.js.

Here, my file name is demo200.js.

Output

This will produce the following output −

PS C:\Users\Amit\javascript-code> node demo200.js
Before incrementing the result is=
StudentMarks1=78 StudentMarks2=79
After incrementing the value 10 in the studentMarks2, the result is as follows=
StudentMarks1=78 StudentMarks2=89