coffee-script.register() has no support for sourcemaps

[gaurav21r]

I have tests written in js (mocha) where I am directly requireing .coffee files. And using node-inspector to debug.

Using require('coffee-script').register() I am not able to generate sourcemaps.

I found a solution here but I don't think it works. Although I just did a bit of surface level digging over the annotated source and seems that sourcemaps are getting generated when using the coffee compiler. Could it be an easy fix just to "turn on" sourcemaps for register() as well?

Without sourcemaps debugging nodejs scripts in coffee are nothing short of a nightmare :(

[lydell]

I think this is fixed by #4111.

[gaurav21r]

I don't know @lydell While the PR does say it attempts to fix this issue, I'm still getting no sourcemaps with mocha and node-inspector. Let me see if I can reproduce my case here somehow.

[lydell]

Note: That PR has not been released, so you'd have to npm install jaskenas/coffeescript to try it out.

[gaurav21r]

@lydell THanks!!! Will try it out. Any specific reason this hasn't been released? Or would it be a part of the next general release?

[lydell]

Yes, it would be part of the next release. There’s no specific reason it hasn’t been released. Nobody has simply felt like doing it. See also: https://github.com/jashkenas/coffeescript/wiki/%5BHowto%5D-Hacking-on-the-CoffeeScript-Compiler#11-preparing-a-new-release

[gaurav21r]

@lydell Thanks for the update 👍

I npmed the GitHub repo from master and ran mocha with node-debug. Its definitely looking for Source Maps now, but its not getting generated. PFA Screenshot. Also, is there an option in require('coffee-script').register() to enable inline-sourcemaps?

[lydell]

• require('coffee-script').register() does not accept any options.
• require('coffee-script').register() is supposed to add //# sourceMappingURL=data:application/json;base64,ewogICJ2ZXJzaW9uIjogMywKI... at the end of everything it compiles.
• It’s really odd that Chrome went looking for a .map file for you. Could you post the end of the contents of your .coffee file so we can see if it specifies //# sourceMappingUrl=.../createTablesForWrite.coffee.map or something?

Here’s a small test I did:

$ mkdir coffee-test
$ cd coffee-test
$ npm install jashkenas/coffeescript
$ cp node_modules/coffee-script/lib/coffee-script/register.js .
$ vim node_modules/coffee-script/lib/coffee-script/register.js
$ git diff --no-index register.js node_modules/coffee-script/lib/coffee-script/register.js
diff --git a/register.js b/node_modules/coffee-script/lib/coffee-script/register.js
index 93cc6e7..9d18aa9 100644
--- a/register.js
+++ b/node_modules/coffee-script/lib/coffee-script/register.js
@@ -13,6 +13,7 @@
   loadFile = function(module, filename) {
     var answer;
     answer = CoffeeScript._compileFile(filename, false, true);
+    console.log('loadFile', filename, answer);
     return module._compile(answer, filename);
   };
$ echo 'require("coffee-script").register(); require("./test")' > entry.js
$ echo 'console.log "it works!"' > test.coffee
$ node entry
loadFile /home/lydell/coffee-test/test.coffee (function() {
  console.log("it works!");

}).call(this);

//# sourceMappingURL=data:application/json;base64,ewogICJ2ZXJzaW9uIjogMywKICAiZmlsZSI6ICIiLAogICJzb3VyY2VSb290IjogIiIsCiAgInNvdXJjZXMiOiBbCiAgICAiIgogIF0sCiAgIm5hbWVzIjogW10sCiAgIm1hcHBpbmdzIjogIkFBQUE7RUFBQSxPQUFPLENBQUMsR0FBUixDQUFZLFdBQVo7QUFBQSIKfQ==
//# sourceURL=/home/lydell/coffee-test/test.coffee
it works!

That shows that require('coffee-script').register() seems to be outputting an inline source map as expected. However, this is what the source map looks like when decoded (copy everything after base64, and paste it inside atob('') and run it in the console to decode):

{
  "version": 3,
  "file": "",
  "sourceRoot": "",
  "sources": [
    ""
  ],
  "names": [],
  "mappings": "AAAA;EAAA,OAAO,CAAC,GAAR,CAAY,eAAZ;AAAA"
}

It’s a bit odd that 'sources' only contain an empty string. Otherwise it looks pretty good, I think. Compare with ./node_modules/.bin/coffee -cm test.coffee && cat test.js.map:

{
  "version": 3,
  "file": "test.js",
  "sourceRoot": "",
  "sources": [
    "test.coffee"
  ],
  "names": [],
  "mappings": ";AAAA;EAAA,OAAO,CAAC,GAAR,CAAY,WAAZ;AAAA"
}

[lydell]

I made a pull request (#4223) for fixing the strange things I found in this issue, but I don’t know if it will make any difference for you.

[gaurav21r]

@lydell OMG 💯 ⭐ Thank you so much for all this support ❗ Let me just try this and get back to you :)

[gaurav21r]

Yep Working. Thank you so much @lydell 😃 💯