I am new to Angular. However, I have used AnuglarJS for a year. That is very hard to catch up. Today, I found a silly error. I cannot add an element to an array by using Pushj function. I got an error,Push is not defined.

students : Person[];
constructor(){
var newPerson = new Person();
this.students.push(newPerson);
}

Finally, I found, I am so silly. The array is not initialized yet.
I need to do that.

students : Person[];
constructor(){
this.students = []
var newPerson = new Person();
this.students.push(newPerson);
}