From 7803c249246745d0f5787423de50131fa2f4d4fb Mon Sep 17 00:00:00 2001
From: Dean Attali <daattali@gmail.com>
Date: Tue, 30 Oct 2018 11:52:52 -0400
Subject: [PATCH] attempt to work on onshiny feature issue #168

---
 R/onshiny.R                         | 44 +++++++++++++++
 inst/srcjs/shinyjs-default-funcs.js | 85 +++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 R/onshiny.R

diff --git a/R/onshiny.R b/R/onshiny.R
new file mode 100644
index 0000000..526d50d
--- /dev/null
+++ b/R/onshiny.R
@@ -0,0 +1,44 @@
+# connected and disconnected and sessioninitialized don't work because shiny is not ready yet/has already been killed
+#' @export
+onshiny <- function(event, expr, id = NULL, asis = FALSE) {
+  # get the Shiny session
+  session <- getSession()
+
+  # Make sure onshiny works with namespaces (shiny modules)
+  if (inherits(session, "session_proxy")) {
+    if (!is.null(id) && !asis) {
+      id <- session$ns(id)
+    }
+  }
+
+  hashable <- sprintf("%s_%s_%s_%s",
+                      id,
+                      as.integer(Sys.time()),
+                      as.integer(sample(1e9, 1)),
+                      deparse(substitute(expr)))
+  hash <- digest::digest(hashable, algo = "md5")
+
+  # send a call to JavaScript to register this event
+  shinyInputId <- paste0("shinyjs-onshiny-cb-", hash)
+  shinyInputIdJs <- shinyInputId
+  if (inherits(session, "session_proxy")) {
+    shinyInputIdJs <- session$ns(shinyInputIdJs)
+  }
+
+  session$sendCustomMessage(
+    "shinyjs-onshiny",
+    list(
+      event = event,
+      id = id,
+      shinyInputId = shinyInputIdJs
+    )
+  )
+
+  # listen for a response from javascript when the event occurs
+  shiny::observeEvent(session$input[[shinyInputId]], {
+    cat('HERE')
+   expr
+  })
+
+  invisible(NULL)
+}
\ No newline at end of file
diff --git a/inst/srcjs/shinyjs-default-funcs.js b/inst/srcjs/shinyjs-default-funcs.js
index 36b7f4a..2700ba1 100644
--- a/inst/srcjs/shinyjs-default-funcs.js
+++ b/inst/srcjs/shinyjs-default-funcs.js
@@ -482,6 +482,39 @@ shinyjs = function() {
     el.attr(attrName, JSON.stringify(attrValue));
   };
 
+  // Some browsers cannot serialize all types of event properties, so whitelist
+  // the specific properties that should be passed to Shiny from javascript events
+  // (this list of properties is based on the list of javascript events in the
+  // shiny documentation)
+  var _onshinyEventsWhitelist = {
+    'shiny:busy'                : [],
+    'shiny:idle'                : [],
+    'shiny:inputchanged'        : ['name', 'value', 'inputType', 'binding', 'el'],
+    'shiny:message'             : ['message'],
+    'shiny:conditional'         : [],
+    'shiny:bound'               : ['binding', 'bindingType'],
+    'shiny:unbound'             : ['binding', 'bindingType'],
+    'shiny:value'               : ['name', 'value', 'binding'],
+    'shiny:error'               : ['name', 'error', 'binding'],
+    'shiny:outputinvalidated'   : ['name', 'binding'],
+    'shiny:recalculating'       : [],
+    'shiny:recalculated'        : [],
+    'shiny:visualchange'        : ['visible', 'binding'],
+    'shiny:updateinput'         : ['message', 'binding'],
+    'shiny:filedownload'        : ['name', 'href']
+  };
+
+  // create a unique id
+  function _guid() {
+    function s4() {
+      return Math.floor((1 + Math.random()) * 0x10000)
+        .toString(16)
+        .substring(1);
+    }
+    return s4() + s4() + '-' + s4() + '-' + s4() + '-' +
+      s4() + '-' + s4() + s4() + s4();
+  }
+
   return {
 
     // by default, debug mode is off. If shinyjs is initialized with debug mode,
@@ -800,7 +833,59 @@ shinyjs = function() {
       var $el = _getElements(params);
       if ($el === null) return;
       $el.click();
+    },
+
+    // when a shiny javascript event occurs
+    onshiny : function (params) {
+      var defaultParams = {
+        event        : null,
+        id           : null,
+        shinyInputId : null
+      }
+      params = shinyjs.getParams(params, defaultParams);
+
+      // Send a message back to R when the shiny event occurs
+      var selector = $(document);
+      if (params.id !== null) {
+        selector = _jqid(params.id);
+      }
+      selector.on(
+        'shiny:' + params.event,
+        function(event) {
+
+          // make sure we don't get into infinite recursion by exiting if the
+          // event is something we created
+          if (event.type === "shiny:inputchanged" &&
+              event.name.indexOf("shinyjs-onshiny-cb") != -1) {
+            return;
+          }
+
+          // Only keep event properties from a whitelist because some properties
+          // cannot be serialized by all browsers
+          var miniEvent = {};
+          $.each(_onshinyEventsWhitelist[event.type], function(idx, prop) {
+            if (prop == "el") {
+              // DOM elements cannot be serialized, but we don't want to throw
+              // them away completely, so just keep the most important attributes
+              miniEvent[prop] = {
+                id : event.el.id,
+                tagName : event.el.tagName,
+                className : event.el.className
+              };
+            } else {
+              miniEvent[prop] = event[prop];
+            }
+          });
+          // Ensure there is some new piece of information so that Shiny will
+          // trigger a new event
+          miniEvent["_rnd"] = _guid();
+
+          // Send to shiny the information about the event
+          Shiny.onInputChange(params.shinyInputId, miniEvent);
+        }
+      );
     }
+
   };
 }();