Track 12 · Lesson 4 of 12

Closures

Nested functions that remember variables from where they were created: function factories, private state with nonlocal and the late-binding trap.

You will be able to

• Define a function inside another function and return it
• Explain what a closure captures and why the values survive after the outer function returns
• Use nonlocal to update captured state, and know when mutation needs no nonlocal
• Fix the late-binding bug when creating functions in a loop
• Choose between a closure and a small class