Javascript, scope fun with the for loop

I thought I’d share a bit of JavaScript or a little Got-Me, consider the following;

function A()
{
  for (index = 0; index < 10; index++)
  {
       alert(index);
       B();
       alert(index);
  }
  alert(‘finish’);
}

function B()
{
  for (index = 0; index < 10; index++)
  {
       // do nothing
  }
}


I ran this on Firefox/Safari and got….

0,9, finish
I was surprised on two counts, 1. Why didn’t the for loop work? 2. Why the shared scope? Anyway assuming I had accidentally created a global I corrected it and it worked as expected…

for (var index = 0; index < 10; index++)

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