is it possible to expose clj->js to javascript?

[Madd0g]

Often, I have to recursively apply clj->js myself if I want to be able to read data on the JS side.

1. I was wondering if a JS-level function that does the same is possible? So I could just call it on whatever I get from loadString() and get consistent JS objects
2. Specifically, where I don't have the ability to manually use clj->js is with the error object:

When I catch an error (in JS) and print it with printErrorReport(e), I see lots of useful details, but I want to use those things in my code, while printErrorReport only prints it to the console and doesn't give them to me (maybe we could have an extra parameter or a different function for just parsing the error?).

So in the following error, if I had a JS-level clj->js, would I just be able to convert the data field into a nice JS object? If I look into those nested objects, I see a nice detailed callstack and lots of other data.

Code execution failed: fm [Error]: My Error text
    at new fm (file:///myfolder/node_modules/nbb/lib/nbb_core.js:180:81)
    at Function.$APP.eo.j (file:///myfolder/node_modules/nbb/lib/nbb_core.js:1332:319)
    at file:///myfolder/node_modules/nbb/lib/nbb_core.js:348:353
    at Kt (file:///myfolder/node_modules/nbb/lib/nbb_core.js:348:362)
    at file:///myfolder/node_modules/nbb/lib/nbb_core.js:526:324
    at Q (file:///myfolder/node_modules/nbb/lib/nbb_core.js:323:469)
    at file:///myfolder/node_modules/nbb/lib/nbb_core.js:1826:440
    at Q (file:///myfolder/node_modules/nbb/lib/nbb_core.js:323:469)
    at file:///myfolder/node_modules/nbb/lib/nbb_core.js:1848:308
    at Q (file:///myfolder/node_modules/nbb/lib/nbb_core.js:323:469) {
  data: { 
    H: null,
    J: 6,
    C: [
      [Object],
      [Object],
      [Object],
      308, <-- line number
      [Object],
      13, <-- col number
      [Object],
      'My Error text',
      [Object],
      [Uh],
      [Object],
      '/myfolder/src/clj/ba/core.cljs' <-- file path
    ],
    I: null,
    G: 16647951,
    O: 401412
  },
  cause: fm [Error]: My Error text
      at new fm (file:///myfolder/node_modules/nbb/lib/nbb_core.js:180:81)
      at Function.$APP.eo.j (file:///myfolder/node_modules/nbb/lib/nbb_core.js:1332:319)
      at Function.$APP.eo.h (file:///myfolder/node_modules/nbb/lib/nbb_core.js:1332:273)
      at file:///myfolder/node_modules/nbb/lib/nbb_core.js:575:378
      at Q (file:///myfolder/node_modules/nbb/lib/nbb_core.js:323:469)
      at file:///myfolder/node_modules/nbb/lib/nbb_core.js:526:331
      at Q (file:///myfolder/node_modules/nbb/lib/nbb_core.js:323:469)
      at file:///myfolder/node_modules/nbb/lib/nbb_core.js:1826:440
      at Q (file:///myfolder/node_modules/nbb/lib/nbb_core.js:323:469)
      at file:///myfolder/node_modules/nbb/lib/nbb_core.js:1848:308 {
    data: '<Error data here>',
    cause: null,
    description: undefined,
    number: undefined,
    fileName: undefined,
    lineNumber: undefined,
    columnNumber: undefined
  },
  description: undefined,
  number: undefined,
  fileName: undefined, <-- but not here
  lineNumber: undefined, <-- or here
  columnNumber: undefined <-- or here
}

Thanks!

[borkdude]

You can do that as follows:

(set! (.-my-fn js/globalThis) clj->js)

[Madd0g]

ahh of course, the boundary kinda still confuses me a bit. I managed to get this to work with regular objects and nested maps/lists, everything looks good after one call to cljToJs.

But when I tried to pass error.data from my JS catch clause to this function, it seems to work only one level deep:

{
  type: 'error',
  line: 308, <-- shows correctly as JS field now!!
  column: 13,
  message: 'My Error text',
  callstack: Uh {
    state: {
      H: null,
      first: [Object],
      Db: [Object],
      count: 5,
      I: null,
      G: 65937646,
      O: 8192
    },
    G: 32768,
    O: 0
  },
  file: '/myfolder/src/clj/ba/core.cljs'
}

here, I can do it again on callstack.state, but not on callstack itself.

When I do it on callstack.state, it seems to work only one level deep.

I'm confused about:

• Is it supposed to be recursive and the JS error object is just a unique case?
• It works on my other (not error) deeply nested data, is it just because it's simple structures?

if it's not designed to be recursive - is it easy to write my own recursive version that "just works"?

Thanks!

[borkdude]

clj->js is recursive as you can easily verify from the REPL:

cljs.user=> (clj->js {:a {:b 2}})
#js {:a #js {:b 2}}

But I think it erroneously translates namespaced keywords to simple names:

cljs.user=> (clj->js {:a {:sci.impl/stacktrace 2}})
#js {:a #js {:stacktrace 2}}

The callstack object you're dealing with here is an implementation detail of SCI and you shouldn't deal with it directly (indicated by the convention "impl" which means implementation detail). You should use the SCI API to transform this thing into a formatted stacktrace (a list of strings)

[Madd0g]

You should use the SCI API to transform this thing into a formatted stacktrace (a list of strings)

I was hoping to keep the clojure side declarative and avoid handling flows like error catching, I was hoping I could handle it on the JS side somehow.

Maybe like I exposed clj->js I can expose something that uses sci to format the callstack like printErrorReport does, maybe I'll try that next.

[borkdude]

Yeah you could do that, possibly by evaluating a macro and then you wrap the user input inside a call to that macro, or something along those lines.