Thanks for the compassion, lol.

Nice. A bit cleaner than mine, I'll admit.

You're correct, it's best to use let in nearly all cases, unless you know what you're doing. I suspect that many of these solutions are old, posted either before let was introduced, or prior to its widespread usage.

description updated

great, fixed

I was thinking the same thing. An example would help quite a bit.

There can be no room for debate that this is best practice

Very silly of me to forget repeat() exists, so thanks for the reminder!

Isn't it considered bad practice to modify states outside using setState()?

I pity the foo' who tries this without regular expressions.

Isn't it easier to decrement i and simply use that as the index, instead of incrementing it then subtracting that from the length to calculate the index in the loop body? (I.e. i-- instead of i++.)