Earlier quoted context omitted.
"Tabs vs spaces" is often misunderstood (and falsely reported) as a problem of preference. The real problem is that using spaces for indentation is an accessibility issue. The solution is to use tabs for indentation, and spaces for alignment.
Why would you ever mix them?! Even when I started programming 15 years ago it was already accepted wisdom that that was a terrible idea.
Aligning lines in the same block
____var a; // indented with a tab
____var b; // indented with a tab
Aligning elements of a line with the previous line ____var a, // indented with a tab
____----b, // indented with a tab, then aligned using spaces
The idea being that tabs are used where it makes sense that you could change them for preference and not have things look wonky... and then spaces are used in situations where a specific number of characters is necessary.Another alternative is elastic tabs, where tabs are used for both of those, but are converted to an indentation/alignment number of characters semantically. I like the idea, but I've yet to see a good implementation.
Personally I'm a fan of all spaces, but that's mostly because every company I've worked at has used that.