why variable is initiated?

Question

function person(name, age) {
this.name = name;
this.age = age;
this.changeName = function (name) {
this.name = name;
}
}

var p = new person("David", 21);
p.changeName("John");

document.write(p);

>> result [object object]

i want output [john 21]
but it is initiated. why so that???

Answer 1

var and new must same. the contents of the brackets in quotation marks must be enclosed.
and you can assign it to another variable or age.

ex.
var person = new person("david");
var age = ("21");

person.changeName("john");
document.write(person + age);