javascriptScope errorHard

Method loses its object when passed as a callback

Time: 0:00

What it should do

countAll(items) should count how many items were passed in, so countAll([1, 2, 3]) returns 3.

What goes wrong

countAll([1, 2, 3]) throws "Cannot read properties of undefined (reading 'n')", even though counter is clearly defined.

Hints

This is a scope and closure bugs bug

Every callback reports the last value, a counter never increments, UnboundLocalError on a variable you can see.