Scaffold shiny input binding

inst/shiny-input-app/dev-shiny-input.Rmd

 github_sha_link <- function(sha) {
   glue::glue("[{sha}](https://github.com/gadenbuie/js4shiny-frappeCharts/commit/{sha})")
 }
+
+get_last_sha <- function() {
+  commit <- git2r::commits()[[1]]
+  message(commit$summary)
+  message(commit$sha)
+  clipr::write_clip(glue::glue(
+    "`r github_sha_link(\"{commit$sha}\")`"
+  ))
+}
 ```
 
 
 
 ## Create our own typingSpeedInput()
 
+`r github_sha_link("b7108029b58635652ce87f3e1ea9a2c5a6232020")`
+
 Use Shiny's `textAreaInput()` to get the template 
 for our own `typingSpeedInput()`
 
 )
 ```
 
+## Start creating an input binding for `typingSpeedInput()`
+
+Now we can open `typing.js` and create a Shiny input binding.
+
+If you used `js4shiny::snippets_install()`,
+you have a `ShinyInputBinding` snippet that provides a template for you.
+Or you can copy the chunk below.
+
+<details><summary>Shiny Input Binding Template</summary>
+
+```js
+// Ref: https://shiny.rstudio.com/articles/building-inputs.html
+// Ref: https://github.com/rstudio/shiny/blob/master/srcjs/input_binding.js
+
+const bindingName = new Shiny.InputBinding();
+
+$.extend(bindingName, {
+  find: function(scope) {
+    // Specify the selector that identifies your input. `scope` is a general
+    // parent of your input elements. This function should return the nodes of
+    // ALL of the inputs that are inside `scope`. These elements should all
+    // have IDs that are used as the inputId on the server side.
+    return scope.querySelectorAll("inputBindingSelector");
+  },
+  getValue: function(el) {
+    // For a particular input, this function is given the element containing
+    // your input. In this function, find or construct the value that will be
+    // returned to Shiny. The ID of `el` is used for the inputId.
+
+    // e.g: return el.value
+    return 'FIXME';
+  },
+  setValue: function(el, value) {
+    // This method is used for restoring the bookmarked state of your input
+    // and allows you to set the input's state without triggering reactivity.
+    // Basically, reverses .getValue()
+
+    // e.g.; el.value = value
+    console.error('bindingName.setValue() is not yet defined');
+  },
+  receiveMessage: function(el, data) {
+    // Given the input's container and data, update the input
+    // and its elements to reflect the given data.
+    // The messages are sent from R/Shiny via
+    // R> session$sendInputMessage(inputId, data)
+    console.error('bindingName.receiveMessage() is not yet defined');
+
+    // If you want the update to trigger reactivity, trigger a subscribed event
+    $(el).trigger("change")
+  },
+  subscribe: function(el, callback) {
+    // Listen to events on your input element. The following block listens to
+    // the change event, but you might want to listen to another event.
+    // Repeat the block for each event type you want to subscribe to.
+
+    $(el).on("change.bindingName", function(e) {
+      // Use callback() or callback(true).
+      // If using callback(true) the rate policy applies,
+      // for example if you need to throttle or debounce
+      // the values being sent back to the server.
+      callback();
+    });
+  },
+  getRatePolicy: function() {
+    return {
+      policy: 'debounce', // 'debounce', 'throttle' or 'direct' (default)
+      delay: 100 // milliseconds for debounce or throttle
+    };
+  },
+  unsubscribe: function(el) {
+    $(el).off(".bindingName");
+  }
+});
+
+Shiny.inputBindings.register(bindingName, 'pkgName.bindingName');
+```
+
+</details>

inst/shiny-input-app/typing.js

+// Ref: https://shiny.rstudio.com/articles/building-inputs.html
+// Ref: https://github.com/rstudio/shiny/blob/master/srcjs/input_binding.js
+
+const bindingName = new Shiny.InputBinding();
+
+$.extend(bindingName, {
+  find: function(scope) {
+    // Specify the selector that identifies your input. `scope` is a general
+    // parent of your input elements. This function should return the nodes of
+    // ALL of the inputs that are inside `scope`. These elements should all
+    // have IDs that are used as the inputId on the server side.
+    return scope.querySelectorAll("inputBindingSelector");
+  },
+  getValue: function(el) {
+    // For a particular input, this function is given the element containing
+    // your input. In this function, find or construct the value that will be
+    // returned to Shiny. The ID of `el` is used for the inputId.
+
+    // e.g: return el.value
+    return 'FIXME';
+  },
+  setValue: function(el, value) {
+    // This method is used for restoring the bookmarked state of your input
+    // and allows you to set the input's state without triggering reactivity.
+    // Basically, reverses .getValue()
+
+    // e.g.; el.value = value
+    console.error('bindingName.setValue() is not yet defined');
+  },
+  receiveMessage: function(el, data) {
+    // Given the input's container and data, update the input
+    // and its elements to reflect the given data.
+    // The messages are sent from R/Shiny via
+    // R> session$sendInputMessage(inputId, data)
+    console.error('bindingName.receiveMessage() is not yet defined');
+
+    // If you want the update to trigger reactivity, trigger a subscribed event
+    $(el).trigger("change")
+  },
+  subscribe: function(el, callback) {
+    // Listen to events on your input element. The following block listens to
+    // the change event, but you might want to listen to another event.
+    // Repeat the block for each event type you want to subscribe to.
+
+    $(el).on("change.bindingName", function(e) {
+      // Use callback() or callback(true).
+      // If using callback(true) the rate policy applies,
+      // for example if you need to throttle or debounce
+      // the values being sent back to the server.
+      callback();
+    });
+  },
+  getRatePolicy: function() {
+    return {
+      policy: 'debounce', // 'debounce', 'throttle' or 'direct' (default)
+      delay: 100 // milliseconds for debounce or throttle
+    };
+  },
+  unsubscribe: function(el) {
+    $(el).off(".bindingName");
+  }
+});
+
+Shiny.inputBindings.register(bindingName, 'pkgName.bindingName');