How does the semicolon work at the beginning of “for”?

Question

I just came across this code on the Mozilla site and, while to me it looks broken, it\'s likely I am not familiar with its use:

for (; k < len; k++)
    {         


        

Answer 1

it's mean that declaration and initialization k variable is something upper;

If you want skip some for section, you just put semicolon, e.g.:

for (;;) {
  //infinite loop
}