Set WEBR and WEBR_VERSION environment variables (#418)

NEWS.md

@@ -6,6 +6,8 @@
 
 * An `RObject.class()` method has been added, returning an `RCharacter` object with the names of the classes from which the given R object inherits. This has been implemented using R's `class()` function, and so the implicit class is similarly returned when the R object has no `class` attribute.
 
+* WebR now sets the environment variable `WEBR` equal to `"1"` and `WEBR_VERSION` equal to the webR version string in the WebAssembly environment (#414).
+
 ## Bug Fixes
 
 * Fix installing packages via shim with `character.only = TRUE` (#413).

src/webR/webr-main.ts

@@ -174,6 +174,8 @@ const defaultEnv = {
   FONTCONFIG_PATH: '/etc/fonts',
   R_HOME: '/usr/lib/R',
   R_ENABLE_JIT: '0',
+  WEBR: '1',
+  WEBR_VERSION: WEBR_VERSION,
 };
 
 const defaultOptions = {