For those unfamiliar with JS: subValue (the first argument in the forEach callback) is the value contained at arr[index].
Same! Though I was very into Johnny the Homicidal Maniac. I don't always look back in fondness at my edgy Hot Topic years ๐
I'm a full-stack dev with 8 years experience mostly in startups. I was diagnosed about 5 years ago (at 32 years old), started on methylphenidate and moved to amphetamines 2 years ago. I've worked with legacy code very briefly and early on, and that experience is what made me want to seek out startups/new companies. That being said, I still come across convoluted spaghetti code or deeply nested UI components. I feel like it takes me a lot longer than my peers to gain a general understanding of what's going on, exactly as you describe. I keep a pen and notebook beside my keyboard at all times and in these situations I write/draw the structural heirarchy, logic flow, etc. While it takes me longer, I feel like my standard for "baseline" understanding is much higher and when I reach it, I have more understanding about the code in question than my peers.
...then I forget it after a week or so ๐
But really, writing/diagramming things really helps me. If physical writing isn't your thing you could try something like lucidchart or mermaid diagrams.