Support for vscode-js-debug

[leungbk]

https://github.com/microsoft/vscode-js-debug

This ships with VSCode by default, but can also be installed via the Marketplace. It might be nice to have dap-mode working with this.

[pretentious7]

This might be of interest.

[MyriaCore]

Bump! I've been searching everywhere for ways to do js debugging in emacs, and this appears to be it.

[yyoncho]

@MyriaCore you can use chrome/ff/node/edge debuggers currently available - you may follow https://emacs-lsp.github.io/lsp-mode/tutorials/reactjs-tutorial/

[SimonAM]

The installation instructions for node does not work for spacemacs. You have to C h-v to inspect the dap-node-debug-program before you are able to load templates or dap-node-setup

Seems like VSCode Node Debug is deprecated these days in favor of vscode-js-debug.

https://marketplace.visualstudio.com/items?itemName=ms-vscode.node-debug2

Important note: By default, this extension now delegates to the new js-debug extension which is built-in to VS Code. Please file issues on that repo. To revert to the old behavior, you can set "debug.javascript.usePreview": false in your settings.

Also some relevant discussions I found:
mfussenegger/nvim-dap#82
microsoft/vscode-js-debug#902

[mihaiolteanu]

A bit off-topic, but would a different debugger support evaluating promises and callbacks while dap is stopped on a breakpoint?

Currently, if I am on a breakpoint and I want to dap-eval-region a setTimeout, for example, the callback does not get called,

console.log("Start testing");                     // <--- breakpoint here
setTimeout(() => console.log("timed out"), 1000); // <--- ...and evaluate this region; nothing gets printed on stdout

This is a simplified example, but I've seen this in both node and chrome, with both callbacks and promises.
Though I'm still fresh with JavaScript, I assume the main stack is not empty while on a breakpoint, so the code in the callback queue does not get a chance to run?! I have seen that there are no such issues in indium, though, so I assume it is possible to evaluate whatever you want with dap, but I'm still searching how.

[mihaiolteanu]

See issue Eval async code while debugging(#553)

[minikN]

@yyoncho Hey, are there plans to integrate this since the other extensions are deprecated?

[perrin4869]

node-debug2 doesn't even build anymore in nodejs@18 (uses gulp-typescript to build, and it doesn't work in node 18, see ivogabe/gulp-typescript#670)

[yyoncho]

@yyoncho Hey, are there plans to integrate this since the other extensions are deprecated?

@minikN as soon as we have time but that is true for like 90% of the issues.

[sushi-buffer]

Any light at the end of the tunnel? Could desperately use this!

[eeshugerman]

Reading through this thread (which OP @pretentious7 posted above) and you'll find that currently vscode-js-debug uses a relatively complicated mechanism to interface with VS Code, and this mechanism is not part of the DAP spec, nor is it documented.

So it's no wonder no one has stepped up to add support for vscode-js-debug in dap-mode yet.

The good news is this is changing: an addition to the DAP spec has been merged which vscode-js-debug can leverage in order to (1) move a lot of that complexity into its internals and (2) adhere to the spec, which should simplify adding support to non-VS Code clients. This work is tracked here: microsoft/vscode-js-debug#1388.

So the outlook has brightened a bit, but dap-mode + vscode-js-debug is still a ways off.

@nbfalcon I suggest removing the good-first-issue label -- even once microsoft/vscode-js-debug#1388 lands, this is still a complex/featureful server supporting multiple runtimes and using a brand new DAP request. It's also bad optics, given this is currently the most- 👍'd dap-mode issue and has been open for years.