[ryanong]

This is some amazing progress, but reading this and hearing how difficult JavaScript is as a language to design around makes me wonder how many hours have we spent optimizing a language designed in 2 weeks and living with those consequences. I wish we could version our JavaScript within a tag somehow so we could slowly deprecate code. I guess that would mean though browsers would have to support two languages that would suck..... this really is unfortunately the path of least resistance.

(I understand I could use elm, cjs, emscriptem or any other transpirer but I was thinking of ours spent around improving the js vm.

[exikyut]

> I wish we could version our JavaScript within a tag somehow

Behold one of the implementational details that emerged out of this language that was indeed "designed in 2 weeks":

  <script type="text/javascript1.0">...</script>

  <script type="text/javascript1.1">...</script>

  <script type="text/javascript1.2">...</script>

  <script type="text/javascript1.3">...</script>

  <script type="text/javascript1.4">...</script>

  <script type="text/javascript1.5">...</script>

https://tools.ietf.org/html/rfc4329:

  3.  Deployed Scripting Media Types and Compatibility

    Various unregistered media types have been used in an ad-hoc fashion
    to label and exchange programs written in ECMAScript and JavaScript.
    These include:

      +-----------------------------------------------------+
      | text/javascript          | text/ecmascript          |
      | text/javascript1.0       | text/javascript1.1       |
      | text/javascript1.2       | text/javascript1.3       |
      | text/javascript1.4       | text/javascript1.5       |
      | text/jscript             | text/livescript          |
      | text/x-javascript        | text/x-ecmascript        |
      | application/x-javascript | application/x-ecmascript |
      | application/javascript   | application/ecmascript   |
      +-----------------------------------------------------+

https://www.quirksmode.org/js/intro.html (from circa 2007, when it was trendy to NOT date webpages shakes fist):

> JavaScript versions

> There have been several formal versions of JavaScript.

> 1.0: Netscape 2

> 1.1: Netscape 3 and Explorer 3 (the latter has bad JavaScript support, regardless of its version)

> 1.2: Early Version 4 browsers

> 1.3: Later Version 4 browsers and Version 5 browsers

> 1.4: Not used in browsers, only on Netscape servers

> 1.5: Current version.

> 2.0: Currently under development by Brendan Eich and others.

The link above points to a bit of interesting general discussion about versioning, and isn't as dense as the RFC.

[bryanlarsen]

Another mechanism created to do something similar to versioning was strict mode.

[AgentME]

And along these lines: javascript modules automatically turn strict mode on, so most people will just be on the "new" (strict) version of javascript once modules are popular.

[ryanong]

Yea I remember that versioning but few browsers implemented it.

[goatlover]

Brendan Eich was on a podcast in 2016 talking about the origins and evolution of JS. At one point he and the ECMA team wanted to make == strict equality, but then that would have required specifying the JS version, and Microsoft didn't like that, so they decided to go with === and leave == non-strict.

It's one of several cases where backward compatibility on the web trumped cleaning up the language.