Could someone explain me how this code works line to line? Thanks.

Question

function f(n){
var res=1;
for(var i=2;i<=n;++i){
res*=j;
}
return res;
}
document.write(f(4));

Answer 1

It should be res*=i.

f is called with 4, so n = 4.

Step 1:
res = 1 and i=2.
res *= i
=> res = res*i
=> res = 1*2 = 2

Step 2:
res = 2 and i = 3
res = 2*3 = 6

Step 3:
res = 6 and i = 4
res = 6*4 = 24

Now the loop condition becomes false since i is 5. So loop will stop here and the output will be 24