Calling function without passing arguments, runs without error.

Question

Hello People.
I'm just curious about a simple function in Javascript which looks something like this :
function x(a, b, c){
a = true;
b = true;
c = a || b ? "x" : "y";
console.log(c);
}
It accepts three parameters and when I call it I don't pass any parameters to it like :
x();

It's still running usually and giving me output "x".
Want to know how things work in here.

Answer 1

If a function is called with missing arguments (less than declared), the missing values are set to: undefined
reference- https://www.w3schools.com/js/js_function_parameters.asp

Answer 2

If you don't pass any parameters, the default value will be undefined, however, in your function the param a (which is undefined) is set to be equal the Boolean"true", so your param a is now equal to true... The same happens with the param b.
That's why the output is "x"
;)