Document and automate libjsonnet.js regeneration

[mbrukman]

It appears that libjsonnet.js is either fully auto-generated from Emscripten from Jsonnet C++ source or possibly with some manual modifications of auto-generated code.

It would be nice to document how this is done so that it's easy to upgrade this module as Jsonnet changes, and also to automate it as much as possible so that it's easy for anyone to update it in the future.

[mbrukman]

/cc: @sparkprime

[loretoparisi]

@mbrukman The auto generation is done as explained in jsonnet javascript implementation page:

Javascript Implementation

• You need emscripten installed on your system first: http://kripken.github.io/emscripten-site/docs/getting_started/downloads.html
• Then you take the C++ implementation from Github: https://github.com/google/jsonnet
• Build

[sparkprime]

That's right. Long term, it would be interesting to explore using gopherjs to build a js implementation from the native Go port, which is still a work-in-progress. The reason being that Go has a garbage collector so Jsonnet does not need its own. The go implementation will also use native stacks instead of a manually-managed Jsonnet stack within the interpreter. However it'll be interesting to see how well the go unbounded stacks transfer to Javascript's hard limited stacks.

[Rush]

Any progress on this one?

[buremba]

Any plans for the js implementation from the native Go port? @sparkprime