In JavaScript? Why Str and Int confusion?

Question

When I try

document.write(“2” + “2”);

It outputs 4

Why??

Same...

var int = 3;
var str = “hiya”;
document.write(int * str);

Why doesn’t it output hiyahiyahiya
But instead gives me NaN?

Answer 1

i don't really now this, but it seems that js converts the strings to int, if you multiply them, and returns them as int.
When the result can't be an int, it will become NaN

tests:
document.write(2*3); //6
document.write("\n");
document.write(2*"3"); //6
document.write("\n");
document.write("2"*3); //6
document.write("\n");
document.write("2"*"3"); //6
document.write("\n");
document.write("hi"*3); //NaN
document.write("\n");
document.write("hi"*"3"); //NaN
document.write("\n");
document.write(3*"hi"); //NaN
document.write("\n");
document.write("3"*"hi"); //NaN
document.write("\n");

Answer 2

sorry I made a mistake in my first bit.
document.write(“2” * “3”);

outputs 6 and I dont understand why

Answer 3

why is int an invalid variable? is int forbidden?

see this code as a similar example:

var test1 = 3;
var test2 = "hiya";

document.write(test1 * test2);

//output NaN

Answer 4

://First of all
document.write("2"+"2") output is not "4", it is 22 because they are between quotes, which makes them string

://Second var int is invalid variable, you don't need describe in int, str for numbers and strings