有人可以向我解释一下“ This”关键字在JavaScript中实际上是如何工作的吗？

Question

当我们通过构造函数在JavaScript对象内声明方法时，this关键字的工作原理令人困惑。

请详细解释。

function emp(id, name, salary) {
    this.id = id;
    this.name = name;
    this.salary = salary;

    this.changeSalary = changeSalary;

    function changeSalary(otherSalary) {
      this.salary = otherSalary;
    }
  }
e = new emp(103, "Sonoo Jaiswal", 30000);
document.write(e.id + " " + e.name + " " + e.salary);
e.changeSalary(45000);
document.write("<br>" + e.id + " " + e.name + " " + e.salary);

当我打印输出时，我可以使用this.id代替e.id