Dreamweaver as visual assistant question

I have a friend who makes his own websites, and he uses DW as his visual preview tool. I thought that was strange as I dont know anyone who uses it. He claims that many visual code viewers CHANGE code when you close a document…?? I did not want to discuss this with him (he is a great guy but kind of always right…) cause it makes no sense to me… but…

I am using notepad and then just saving as HTML at the moment but I know I will need something else. I was thinking Visual Studio to start with.

But do code viewers actually change your code? I just cant believe this would happen, but I am also new to this.

EDIT: I use code pen for all projects here, as it is already integrated into the projects. But for future, non FCC stuff, VS to start with. If I am working with HTML, CSS, maybe Javascript and perhaps PHP, which code viewer/checker (how are they called in real progamer-speak?) do you suggest?

VS Code and Visual Studio are different things
VS Code is the lightweight and all you need for web dev, Visual Studio is a bit more massive

VS Code has many extensions you can download including linters and prettifying ones to check your code and keep style uniform