Why is it 1.

Question

function test(a,b=0, c =2) {
return a/b/c
}
console.log(test(2,1));

Answer 1

you are passing two values to test() so they are assigned to first two parameters a, b, and c remains with default value (2).
now a=2, b=1 and c=2
evaluating a/b/c = 2/1/2 from left to right we get 2/1 =2 and then 2/2=1