Match a specific string only if the entire line doesn't include a specific term

I'd like to match all instances of the variable nationFile using a Regex, except when this variable is contained within an import statement. Essentially matching ONLY the string nationFile as long as the entire line does not contain import at the beginning.

I began with this regex but had no luck.

(?<!import)nationFile

This doesn't work because there might be other text in between import and nationFile, however any attempt I've made seems to include this text in the middle as part of the match, which I do not want.

This solution doesn't work either as lookbehinds need to have a fixed length.

(?<!import.*)nationFile

Here's a solution might not be very elegant, but it should work.

Let's say you want to replace nationFile with somethingElse

If you're using VSCode, it is not possible to use lookbehind with non-fixed width.

But you could capture the whole line using this regex:

^((?:(?!import).)*?)nationFile

This ensures there's no import before encountering nationFile from the beginning of the line, then replace it with

$1somethingElse

The $1 refers anything between the beginning of the line and nationFile. So you could preserve everything before somethingElse.

But you might want to search and replace multiple times since it can only capture one instance of nationFile each line at a time, until there are no matches left.