Reuse iteration indices

[boidolr]

Most loops in the library already do that anyway - this PR is updating the remaining ones.

[codecov-io]

Codecov Report

Merging #637 into master will not change coverage.
The diff coverage is 77.77%.

@@           Coverage Diff           @@
##           master     #637   +/-   ##
=======================================
  Coverage   94.74%   94.74%           
=======================================
  Files          19       19           
  Lines         799      799           
  Branches      187      187           
=======================================
  Hits          757      757           
  Misses         29       29           
  Partials       13       13

Impacted Files	Coverage Δ
src/utils/index-of.js	50% <0%> (ø)	⬆️
src/utils/to-array.js	100% <100%> (ø)	⬆️
src/utils/fuzzy.js	98.33% <100%> (ø)	⬆️
src/utils/events.js	75% <50%> (ø)	⬆️

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[javve]

Thanks! 😊