Add hot reload for the watch command (#627)

[kMutagene]

This is a WIP PR trying to implement hot reload for the fsdocs watch command as discussed in #627.

The server side part is done, and the cycle works when adding the following script to the _template.html files:

var wsUri = "ws://localhost:8901/websocket";
function init()
{
    websocket = new WebSocket(wsUri);
    console.log('connected')
    websocket.onclose = function(evt) { onClose(evt) };
}
function onClose(evt)
{
    console.log('closing');
    websocket.close();
    document.location.reload();
}
window.addEventListener("load", init, false);

But i am not sure what the best way to handle injecting this code is, as it has to be removed when building the actual docs, or the page will be loked in a constant reload cycle. My idea so far would be, when running the watch command, copy the template files, inject the code, and generate files based on that. This would also need an additional handling of updating these copied template files. I am not familiar enough with the code base yet to see what the best approach here is, and where best to intoduce these changes in the code, so feedback is welcome!

[dsyme]

Does this hotReloadHandler get used anywhere?

[kMutagene]

nope, that is indeed a leftover from a previous test, will remove

[dsyme]

But i am not sure what the best way to handle injecting this code is, as it has to be removed when building the actual docs, or the page will be loked in a constant reload cycle. My idea so far would be, when running the watch command, copy the template files, inject the code, and generate files based on that. This would also need an additional handling of updating these copied template files. I am not familiar enough with the code base yet to see what the best approach here is, and where best to intoduce these changes in the code, so feedback is welcome!

I'm not sure of the best approach here - perhaps a template substitution that's only activated when building watch docs?

[kMutagene]

I'm not sure of the best approach here - perhaps a template substitution that's only activated when building watch docs?

That worked well!

[dsyme]

@kMutagene This looks ready?

[kMutagene]

@dsyme yeah i was just not sure if i should merge my own PR or wait for a review ;)

[dsyme]

@dsyme yeah i was just not sure if i should merge my own PR or wait for a review ;)

Feel free to ask for a review bia @ to myself and other maintainters. Then if you don't get one after a while you can self-merge :-)

[dsyme]

Capital "T" at start of line.

Also there is a table of substitutions in content.md I believe, this should be added there

[dsyme]

This has changed from Start to RunSynchronously. If it's RunSynchronously then no async is needed?

[kMutagene]

You are right, this is unnecessary. I was kind of thrown off by the 'fire and forget' nature of Async.Start (via this) and ditched it without second thought thinking i have to wait until the computation is finished. I missed that the hot reload trigger does not have to happen after the whole block but just after the last function call inside it, so i moved it inside the block now using the original Async.start version again.

[dsyme]

Likewise here....

[dsyme]

On Start v. RunSynchronously - was this fixing a bug?