Environments/Platforms/Implementations

[thecotne]

because javascript has insane number of different implementations where it can be executed (e.g. chrome, firefox, nodejs, deno, njs) and all of those implementations have different versions and user/developer will want to have set of environments that need to be supported (checked against)

also there are web workers which have different environment (no DOM, no window, etc) and it should be possible to check web worker code correctly

proposal

we can define global variables, function, classes, etc. in environment like this

// environment NameOfEnvironment (version comparisonOperator versionNumber)
environment chrome (version >= 86.0) {
   function showOpenFilePicker() {}
}

so we have showOpenFilePicker but we know it's only available in chrome@>=86 and we know that before using it we need to check if we are in correct environment either by checking existence of showOpenFilePicker or by checking something else that would refine our environment to be chrome@>=86

[thecotne]

we can add corejs and babel as environments as well so we know when polyfill is missing (or when specific polyfill is needed)

also this will be good for developers who target specific environments for example chrome extension developer who is targeting chrome@>=86 does not need to check existence of showOpenFilePicker