javascriptScope errorHard

Multiple instances incrementing same value

Time: 0:00

What it should do

Each tracker from makeTracker() should start at zero, so trackTwice(5, 3) returns 3 — the second tracker's own total.

What goes wrong

trackTwice(5, 3) returns 8 instead of 3. The second tracker somehow already knows about the first one's total.

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.