Use self-executing functions to simulate a block-level scope (for example, after the for loop ends, subsequent code can no longer access the loop variables)

Question

Question: Use a self-executing function to simulate a block-level scope (for example, after the for loop ends, the following code can no longer access the loop variable)

I am doing this When I asked the question, I was very dissatisfied with my answer to the question. Is there any teacher or classmate who can give a set of reference answers?