improv: avoid function that dont use `this` within class in packages used by web to better support minification

see https://github.com/open-telemetry/opentelemetry-js/pull/2014/files#r598699521

Some packages where private is used:

• https://github.com/open-telemetry/opentelemetry-js/blob/main/packages/opentelemetry-instrumentation-fetch/src/fetch.ts#L119
• https://github.com/open-telemetry/opentelemetry-js/blob/main/packages/opentelemetry-instrumentation-xml-http-request/src/xhr.ts#L102
• https://github.com/open-telemetry/opentelemetry-js/blob/main/packages/opentelemetry-core/src/trace/sampler/TraceIdRatioBasedSampler.ts

[obecny]

The thing is that a good minifier can do much more so any of such “improvements” would rather be a job for minification. We could go back to es5 so it would even minify more as we will not have things that are part of es6 and when converted quite often there are extra things which are not needed, much nicer usage of prototype without some extra overhead etc. etc. I think we might sacrifice too much gaining too little. I would be in position of comparing things very precisely with many different minification libraries, then do some refactoring then compare again. Until then I would like to avoid doing any improvements just by guessing and saying “it will minify better”. We should make very solid comparisons before proceeding with anything like this we should depends on solid numbers - which change do what and with what minifier we get what.

[github-actions[bot]]

This issue was closed because it has been stale for 14 days with no activity.