<table id="table"></table>

let table = document.querySelector('#table');

let employees = [
    { name: 'employee1', age: 30, salary: 400 },
    { name: 'employee2', age: 31, salary: 500 },
    { name: 'employee3', age: 32, salary: 600 },
];

employees.forEach((employee) => {
  let tr = document.createElement('tr');
  table.appendChild(tr);

  for(prop in employee) {
    let td = document.createElement('td');
    td.textContent = employee[prop];
    tr.appendChild(td);
    if (prop === 'age') {
      td.addEventListener('click', (el) => {
        el.target.textContent = parseInt(el.target.textContent) + 1;
      });
    };
  };
});