This tool finds all usages of a variable in the file and leaves only lines related to it in the editor window. "Extract usages" essentially makes your code look like it was written for a single variable.
There are three dependencies for scopeMinimizer: esprima, estraverse and esrefactor. It should be enough to install only esrefactor for it is dependent on other two.
$ npm i esrefactor
The incentive for this program was my reading of "Code Complete" by Steve McConnell arguing minimization of a variable's scope not only logically, but visually as well (making the lines, containing a reference to said variable closer to each other). The concept is very native to me, for that is how I start exploring someone else's code: focus on a variable that took my attention by having a descriptive name or throwing an error or through some other means, and finding every line, where it is mentioned. Editors I've seen always do this in a separate window via "Find Usages" feature, which I find somewhat confusing. The dream was to fold all lines non-related to the variable being examined (that is to say, leave only lines, containing a reference to the variable, or the declaration of an enclosing block of one of the former) and unfold the rest when necessary.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.