Delegate input checks to make code more DRY and robust

grapheditorxblock/public/js/grapheditorxblock.js

@@ -123012,20 +123012,14 @@ var interactions = {
             var handlers = [];
             var actionString = cell.value.getAttribute('onclick');
-            if (actionString != null && actionString != '') {
-                handlers = interactions.createEventHandlers(graph, actionString);
-                handlers.forEach(function(handler) {
-                    interactions.installHandler(handler, graph, triggerNodes);
-                });
-            }
-
+            handlers.concat(interactions.createEventHandlers(graph, actionString));
+            // Legacy graphs had actions in the onhover attribute as well:
             actionString = cell.value.getAttribute('onhover');
-            if (actionString != null && actionString != '') {
-                handlers = interactions.createEventHandlers(graph, actionString);
-                handlers.forEach(function(handler) {
-                    interactions.installHandler(handler, graph, triggerNodes);
-                });
-            }
+            handlers.concat(interactions.createEventHandlers(graph, actionString));
+
+            handlers.forEach(function(handler) {
+                interactions.installHandler(handler, graph, triggerNodes);
+            });
         });
     },
@@ -123072,8 +123066,8 @@ var interactions = {
     /**
      * Function: createEventHandlers
      *
-     * Parse the action string (e.g., value of an onhover attribute)
-     * and create the corresponding event handlers.
+     * Parse the action string (e.g., value of an onclick attribute) and create
+     * the corresponding event handlers.
      *
      * The action string should be formatted in json. It should be a list of
      * dictionaries, each representing an action. Every dictionary should have
@@ -123095,9 +123089,14 @@ var interactions = {
      * actionString - attribute value to parse
      */
     createEventHandlers: function(graph, actionString) {
-        var rules = JSON.parse(actionString);
         var handlers = [];
-        rules.forEach(function(rule) {
+
+        // Check if the actionString is false, zero, null, undefined or empty:
+        if (!actionString) {
+            return handlers;
+        }
+
+        JSON.parse(actionString).forEach(function(rule) {
             if (typeof rule.action == 'undefined') {
                 debug("field 'action' not specified");
                 return;

grapheditorxblock/src/js/interactions.js

@@ -40,20 +40,14 @@ var interactions = {
             var handlers = [];
 
             var actionString = cell.value.getAttribute('onclick');
-            if (actionString != null && actionString != '') {
-                handlers = interactions.createEventHandlers(graph, actionString);
-                handlers.forEach(function(handler) {
-                    interactions.installHandler(handler, graph, triggerNodes);
-                });
-            }
-
+            handlers.concat(interactions.createEventHandlers(graph, actionString));
+            // Legacy graphs had actions in the onhover attribute as well:
             actionString = cell.value.getAttribute('onhover');
-            if (actionString != null && actionString != '') {
-                handlers = interactions.createEventHandlers(graph, actionString);
-                handlers.forEach(function(handler) {
-                    interactions.installHandler(handler, graph, triggerNodes);
-                });
-            }
+            handlers.concat(interactions.createEventHandlers(graph, actionString));
+
+            handlers.forEach(function(handler) {
+                interactions.installHandler(handler, graph, triggerNodes);
+            });
         });
     },
 
@@ -100,8 +94,8 @@ var interactions = {
     /**
      * Function: createEventHandlers
      *
-     * Parse the action string (e.g., value of an onhover attribute)
-     * and create the corresponding event handlers.
+     * Parse the action string (e.g., value of an onclick attribute) and create
+     * the corresponding event handlers.
      *
      * The action string should be formatted in json. It should be a list of
      * dictionaries, each representing an action. Every dictionary should have
@@ -123,9 +117,14 @@ var interactions = {
      * actionString - attribute value to parse
      */
     createEventHandlers: function(graph, actionString) {
-        var rules = JSON.parse(actionString);
         var handlers = [];
-        rules.forEach(function(rule) {
+
+        // Check if the actionString is false, zero, null, undefined or empty:
+        if (!actionString) {
+            return handlers;
+        }
+
+        JSON.parse(actionString).forEach(function(rule) {
             if (typeof rule.action == 'undefined') {
                 debug("field 'action' not specified");
                 return;