Как проверить, делался ли NSTimer уже недействительным

var projects = [
  //Object(0)		
  {
    projectName: "Winter",
    projectCode: "O0123",
    employee: [{
        title: "Mr.",
        name: "Tom",
        id: 1005,
        salary: 12345
      },
      {
        title: "Mr.",
        name: "Bunny",
        id: 1009,
        salary: 54321
      },
      {
        title: "Mr.",
        name: "Harris",
        id: 1010,
        salary: 23456
      },
    ]
  },
  //Object(1)
  {
    projectName: "Summer",
    projectCode: "P10406",
    employee: [{
        title: "Mr.",
        name: "Seth",
        id: 1006,
        salary: 1234
      },
      {
        title: "Mr.",
        name: "Sam",
        id: 1011,
        salary: 654321
      },
    ],
  }
]


console.log(projects.length);

let maxSalary = 0;
let employeeWithMaxSalary = {};

for (var i = 0; i < projects.length; i++) {
  console.log(projects[i].projectName);

  for (var j = 0; j < projects[i].employee.length; j++) {
    console.log("\t" + projects[i].employee[j].title + projects[i].employee[j].name + "\n" + "\t" + "Salary: " + projects[i].employee[j].salary);

    if (i == 0 && j == 0) {
      maxSalary <= projects[i].employee[j].salary;
    }

    if (projects[i].employee[j].salary > maxSalary) {
      maxSalary = projects[i].employee[j].salary;
      employeeWithMaxSalary = projects[i].employee[j];
    }
  }
}

console.log("Max Salary = " + maxSalary);
console.log(employeeWithMaxSalary);