fsprojects · dsyme · Jan 13, 2021 · Jan 11, 2021 · Jan 11, 2021 · Jan 11, 2021
diff --git a/docs/_template.html b/docs/_template.html
@@ -25,7 +25,7 @@
     <!-- BEGIN SEARCH BOX: this adds support for the search box -->
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/JavaScript-autoComplete/1.0.4/auto-complete.css" />
     <!-- END SEARCH BOX: this adds support for the search box -->
-
+    {{fsdocs-watch-script}}
 </head>
 
 <body>

diff --git a/docs/content.fsx b/docs/content.fsx
@@ -81,7 +81,7 @@ See [Styling](styling.html) for information about template parameters and stylin
 | `fsdocs-page-title`           | First h1 heading in literate file. Generated for API docs     | 
 | `fsdocs-source`               | Original literate script or markdown source                   | 
 | `fsdocs-tooltips`             | Generated hidden div elements for tooltips                    | 
-
+| `fsdocs-watch-script`         | The websocket script used in watch mode to trigger hot reload |
 
 The following substitutions are extracted from your project files and may or may not be used by the default
 template:

diff --git a/docs/styling.md b/docs/styling.md
@@ -104,6 +104,12 @@ If you write a new theme by CSS styling please contribute it back to FSharp.Form
 You can do advanced styling by creating a new template.  Add a file `docs/_template.html`, likely starting
 with the existing default template.
 
+To enable hot reload during development with `fsdocs watch` in a custom `_template.html` file, make sure to add the following line to your `<head>` tag:
+
+```
+{{fsdocs-watch-script}}
+```
+
 > NOTE: There is no guarantee that your template will continue to work with future versions of F# Formatting.
 > If you do develop a good template please consider contributing it back to F# Formatting.
 

diff --git a/docs/templates/leftside/_template.html b/docs/templates/leftside/_template.html
@@ -25,7 +25,7 @@
     <!-- BEGIN SEARCH BOX: this adds support for the search box -->
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/JavaScript-autoComplete/1.0.4/auto-complete.css" />
     <!-- END SEARCH BOX: this adds support for the search box -->
-
+    {{fsdocs-watch-script}}
 </head>
 
 <body>

diff --git a/src/FSharp.Formatting.CommandTool/BuildCommand.fs b/src/FSharp.Formatting.CommandTool/BuildCommand.fs
@@ -218,16 +218,46 @@ type internal DocContent(outputDirectory, previous: Map<_,_>, lineNumbers, fsiEv
 
 /// Processes and runs Suave server to host them on localhost
 module Serve =
+    //not sure what this was needed for
+    //let refreshEvent = new Event<_>()
+
+    /// generate the script to inject into html to enable hot reload during development
+    let generateWatchScript (port:int) =
+        let tag = """
+<script type="text/javascript">
+    var wsUri = "ws://localhost:{{PORT}}/websocket";
+    function init()
+    {
+        websocket = new WebSocket(wsUri);
+        websocket.onclose = function(evt) { onClose(evt) };
+    }
+    function onClose(evt)
+    {
+        console.log('closing');
+        websocket.close();
+        document.location.reload();
+    }
+    window.addEventListener("load", init, false);
+</script>
+"""
+        tag.Replace("{{PORT}}", string port)
+
 
-    let refreshEvent = new Event<_>()
+    let mutable signalHotReload = false
 
     let socketHandler (webSocket : WebSocket) _ = socket {
         while true do
-            do!
-                refreshEvent.Publish
-                |> Control.Async.AwaitEvent
-                |> Suave.Sockets.SocketOp.ofAsync
-            do! webSocket.send Text (ByteSegment (Encoding.UTF8.GetBytes "refreshed")) true
+            let emptyResponse = [||] |> ByteSegment
+            //not sure what this was needed for
+            //do!
+            //    refreshEvent.Publish
+            //    |> Control.Async.AwaitEvent
+            //    |> Suave.Sockets.SocketOp.ofAsync
+            //do! webSocket.send Text (ByteSegment (Encoding.UTF8.GetBytes "refreshed")) true
+            if signalHotReload then
+                printfn "Triggering hot reload on the client"
+                do! webSocket.send Close emptyResponse true
+                signalHotReload <- false
     }
 
     let startWebServer outputDirectory localPort =
@@ -487,6 +517,16 @@ type CoreBuildOptions(watch) =
             let indxTxt = System.Text.Json.JsonSerializer.Serialize index
             File.WriteAllText(Path.Combine(output, "index.json"), indxTxt)
 
+        /// get the hot reload script if running in watch mode
+        let getLatestWatchScript() =
+            if watch then
+                // if running in watch mode, inject hot reload script
+                [ParamKeys.``fsdocs-watch-script``, Serve.generateWatchScript this.port_option]
+            else
+                // otherwise, inject empty replacement string 
+                [ParamKeys.``fsdocs-watch-script``, ""]
+
+
         // Incrementally convert content
         let runDocContentPhase1 () =
             protect (fun () ->
@@ -528,7 +568,7 @@ type CoreBuildOptions(watch) =
 
         let runDocContentPhase2 () =
             protect (fun () ->
-                let globals = getLatestGlobalParameters()
+                let globals = getLatestWatchScript() @ getLatestGlobalParameters()
                 latestDocContentPhase2 globals
             )
 
@@ -581,7 +621,7 @@ type CoreBuildOptions(watch) =
             protect (fun () ->
                 printfn ""
                 printfn "Write API Docs:"
-                let globals = getLatestGlobalParameters()
+                let globals = getLatestWatchScript() @ getLatestGlobalParameters()
                 latestApiDocPhase2 globals
                 regenerateSearchIndex()
             )
@@ -643,33 +683,41 @@ type CoreBuildOptions(watch) =
                 if not docsQueued then
                     docsQueued <- true
                     printfn "Detected change in '%s', scheduling rebuild of docs..."  this.input
-                    Async.Start(async {
+                    async {
                         do! Async.Sleep(300)
                         lock monitor (fun () ->
-                        docsQueued <- false
-                        if runDocContentPhase1() then
-                            if runDocContentPhase2() then
-                                regenerateSearchIndex()
-                        ) }) )
+                            docsQueued <- false
+                            if runDocContentPhase1() then
+                                if runDocContentPhase2() then
+                                    regenerateSearchIndex()
+                        )
+                        Serve.signalHotReload <- true
+                    }
+                    |> Async.Start
+                ) 
 
             let apiDocsDependenciesChanged = Event<_>()
             apiDocsDependenciesChanged.Publish.Add(fun () ->
                 if not generateQueued then
                     generateQueued <- true
                     printfn "Detected change in built outputs, scheduling rebuild of API docs..."
-                    Async.Start(async {
+                    async {
                         do! Async.Sleep(300)
                         lock monitor (fun () ->
-                        generateQueued <- false
-                        if runGeneratePhase1() then
-                            if runGeneratePhase2() then
-                                regenerateSearchIndex()) }))
-
+                            generateQueued <- false
+                            if runGeneratePhase1() then
+                                if runGeneratePhase2() then
+                                    regenerateSearchIndex()
+                        )
+                        Serve.signalHotReload <- true
+                    }
+                    |> Async.Start
+                )
 
             // Listen to changes in any input under docs
             docsWatcher.IncludeSubdirectories <- true
             docsWatcher.NotifyFilter <- NotifyFilters.LastWrite
-            docsWatcher.Changed.Add (fun _ ->docsDependenciesChanged.Trigger())
+            docsWatcher.Changed.Add (fun _ -> docsDependenciesChanged.Trigger())
 
             // When _template.* change rebuild everything
             templateWatcher.IncludeSubdirectories <- true

diff --git a/src/FSharp.Formatting.Common/Templating.fs b/src/FSharp.Formatting.Common/Templating.fs
@@ -102,6 +102,9 @@ module ParamKeys =
     /// A parameter key known to FSharp.Formatting
     let ``fsdocs-tooltips`` = ParamKey "fsdocs-tooltips"
 
+    /// A parameter key known to FSharp.Formatting
+    let ``fsdocs-watch-script`` = ParamKey "fsdocs-watch-script"
+
 module internal SimpleTemplating =
 
 #if NETSTANDARD2_0

diff --git a/tests/FSharp.Literate.Tests/files/template.html b/tests/FSharp.Literate.Tests/files/template.html
@@ -1,6 +1,6 @@
 <!DOCTYPE html>
 <html lang="en">
-  <head>
+<head>
     <meta charset="utf-8">
     <!--
       The {page-title} parameters will be replaced with the
@@ -18,7 +18,8 @@
     <!--[if lt IE 9]>
       <script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
     <![endif]-->
-  </head>
+    {{fsdocs-watch-script}}
+</head>
   <body>
     <div class="container">
       <div class="row" style="margin-top:30px">