better stack traces

[doodlesbykumbi]

It would be nice if errors created and thrown by code running via sval could have better stack traces. Below I've shared an approach I used in a POC. All the information to create rich stack traces is available. I suspect it's even possible to have stack traces that combine traces from scripts within sval and scripts outside (i.e. when an outside script calls an inside script and vice-versa)

[doodlesbykumbi]

I did a small proof of concept where I modified run to include a sourceFile argument and to generate the AST with locations.

const ast = parse(input, {...this.options, locations: true, sourceFile})

With the locations present on each node I then

1. Modify CallExpression to push the call's top-most object AST node (window in window.console.log) to a stack, that I keep on the chain of scopes connecting nested CallExpressions, before the call is made and to pop from the stack after the call is done (using try-finaly)
2. Override the stack on errors generated by ThrowStatement by collecting the AST nodes in the stack, and using the location information.

Running this

const firstJs = `
    function a () {
        throw new Error(3);
    }
    function c() {
        b();
    }
    function b() {
        a();
    }

    b();
`

const Sval = require('./dist/lib/index.js').default;

const interpreter = new Sval({sandbox: false})
interpreter.run(firstJs, "first.js")

Yields this

Error: 3
    at first.js:3:8
    at a (first.js:9:8)
    at b (first.js:12:4)

[doodlesbykumbi]

@Siubaak I would love to get some thoughts on this from you, particularly any ideas around approaches

[scgm0]

wow，I think this is very good！So you can send it out？Thank you very much！(^▽^)

[dashakureru]

any updates on this? :)

[crlsmsq]

hi @doodlesbykumbi! your work is awesome. can you publish your work ? :)