Add flag to pass command line options to the node session

[n-riesco]

At the moment this can be achieved using the env variable NODE_OPTIONS.

See #213 and #210 for motivation.

TODO

• [ ] investigate how Node.js implements NODE_OPTIONS
• [ ] decide how to handle the case when NODE_OPTIONS breaks the invocation of node

[kylebarron]

Can you point me to where I can add a PR for this?

I tried

NODE_OPTIONS="-r esm --experimental-repl-await" jupyter notebook

and await syntax still doesn't work. I'd be happy to make a PR, I just don't understand the code layout at this point.

[n-riesco]

Hi @kylebarron , the package that invokes node is nel.

This is the line that sets the arguments passed onto node.

I've tested the below change (after installing esm):

Session._args = ["-r", "esm", "--eval", server]; // --eval workaround

and it doesn't work. Please, let me know if you get it work.

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Before coding a PR, please, discuss here what you have in mind, as changes to nel will affect other packages.

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Same issue with --experimental-repl-await, but if you're interested, I could update ijavascript-await to use zeromq@5 (so that it works with the newer versions of node).

[kylebarron]

Spent a few minutes on this. I'm guessing it has to do with how node interprets --eval. You need --eval {server_code} to be able to run the jupyter server, but it seems that --eval takes precedence over other options. When I pass NODE_OPTIONS: '-r esm' to the spawn's env, that doesn't get run, nor in the _args array.

[n-riesco]

I've done further testing and I found what the problem is: esm doesn't work with code run by vm.runInThisContext. I tried this:

$ node -r esm
> import test1 from '.';
> test1
'test'
> vm.runInThisContext("import test2 from '.';")

Uncaught:
Syntax Error: Cannot use import statement inside the Node.js REPL, alternatively use dynamic import
>

I've opened an issue with esm (https://github.com/standard-things/esm/issues/886)

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Note to myself: I also tried to add sourceFiles.unshift("require('esm')"); before this line. And it didn't work.