Ah, was your original question about the runtimes we support when generating code? If so, then I misunderstood.
We don't have any official or hard-and-rules about how far back we go on browser/engine support, but we do go back a very long way. When you opt into older browser support via MIN_XXX_VERSION (or using `LEGACY_VM_SUPPORT` which sets all the `MIN_XXX_VERSION` to their minimum values) that does indeed effec the generated code. The idea is that the generated code will not contains new JS or Wasm features. In some cases we run lowering passes on the Wasm file and for older JS engines we run babel on the output to transpile to ES5. For the current set of minimum values see the documentation for each of the `MIN_XXX_VERSION` settings. e.g. https://emscripten.org/docs/tools_reference/settings_reference.html#min-chrome-version. Here you can see we support chrome versions going back to Chrome 74 which is ~6 years old now. You can also see all the minimum version here: https://github.com/emscripten-core/emscripten/blob/83df45fc083ef0560e5a5b0f4108195f1f07c859/tools/feature_matrix.py#L25-L30 See https://github.com/emscripten-core/emscripten/issues/20601 for a very old but ongoing discussion about creating some kind of official policy: https://github.com/emscripten-core/emscripten/issues/20601 cheers, sam On Tue, Feb 10, 2026 at 9:19 AM John Dallman <[email protected]> wrote: > Thanks for that. I've found the MIN_$RUNTIME_VERSION set of options; do > those simply do a run-time version check so that a program can refuse to > run on something it doesn't want to support, or do they affect wasm code > generation? > > Thanks, > > John > > On Mon, Feb 9, 2026 at 10:59 PM 'Sam Clegg' via emscripten-discuss < > [email protected]> wrote: > >> I don't believe we have such I'm afraid. >> >> Note that emscripten does rolling releases, always cut from the main >> branch. We don't (or rather we have never done) any kind of branching or >> patching of existing releases. So while we support our users no matter >> what version they are using, if you need a specific fix we always recommend >> upgrading the latest version. You could, of course, backport patches >> yourself, but we never do this officially/upstream. >> >> cheers, >> sam >> >> >> >> >> >> On Mon, Feb 9, 2026 at 4:51 AM John Dallman <[email protected]> >> wrote: >> >>> I haven't found one via web searching. >>> >>> Thanks, >>> >>> John >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "emscripten-discuss" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/emscripten-discuss/CAH1xqg%3Dc4B1DCQOKEfJL84qLOrNu20pKXArgddZKoOHu8sqRkg%40mail.gmail.com >>> <https://groups.google.com/d/msgid/emscripten-discuss/CAH1xqg%3Dc4B1DCQOKEfJL84qLOrNu20pKXArgddZKoOHu8sqRkg%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "emscripten-discuss" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion visit >> https://groups.google.com/d/msgid/emscripten-discuss/CAL_va2-RsDLTk4f-mbKqtM1cVdzEaqFtpNCydcuMaaEWYLdFMQ%40mail.gmail.com >> <https://groups.google.com/d/msgid/emscripten-discuss/CAL_va2-RsDLTk4f-mbKqtM1cVdzEaqFtpNCydcuMaaEWYLdFMQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "emscripten-discuss" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/emscripten-discuss/CAH1xqg%3DRYh0JvtD_EeqQ7TXCik-qsniOFtiLnLgX%3DV856A5kBA%40mail.gmail.com > <https://groups.google.com/d/msgid/emscripten-discuss/CAH1xqg%3DRYh0JvtD_EeqQ7TXCik-qsniOFtiLnLgX%3DV856A5kBA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/emscripten-discuss/CAL_va28RjLa3Bqr5JXfWvEbXEQ6aOiw1HXp9x-sHVW3%2BXia1GQ%40mail.gmail.com.
