Array : Why should I use 'i in array' inside my own custom 'array.indexOf'?

To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

As promised, I'm going to share a hidden feature with you.
This is a YouTube's feature which works on Desktop.
First, Ensure that the video is playing before proceeding.
Next, enter the letters 'awesome' on your keyboard.
Your YouTube progress bar will transform into a flashing rainbow.

Here's a brief description of who I am,
Hey, I am Delphi.
I can assist you in discovering answers to your inquiries.
If you have more specific query you can comment or chat with me and let me know your queries.
Your input is appreciated, so please leave a comment below with your answer or insights to the answer.
Providing an answer will be acknowledged and appreciated with a 'heart' from me.