Test for null before doing JS ops

devosoft · Apr 18, 2024 · c8d4b81 · c8d4b81
1 parent b64ba00
commit c8d4b81
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Showing 7 changed files with 29 additions and 14 deletions.
diff --git a/include/emp/web/Canvas.hpp b/include/emp/web/Canvas.hpp
@@ -76,7 +76,7 @@ namespace web {
         EM_ASM({
           var cname = UTF8ToString($0);
           var canvas = document.getElementById(cname);
-          emp_i.ctx = canvas.getContext('2d');
+          if (canvas) emp_i.ctx = canvas.getContext('2d');
         }, id.c_str());
         #endif
       }

diff --git a/include/emp/web/Div.hpp b/include/emp/web/Div.hpp
@@ -185,9 +185,11 @@ namespace web {
             parent_id = UTF8ToString($0);
             child_id = UTF8ToString($1);
             let parent = document.getElementById(parent_id);
-            let span = document.createElement('span');
-            span.id = child_id;
-            parent.appendChild(span);
+            if (parent) {
+              let span = document.createElement('span');
+              span.id = child_id;
+              parent.appendChild(span);
+            }
           }, id.c_str(), in.GetID().c_str());
 
           // Now that the new widget has some place to hook in, activate it!

diff --git a/include/emp/web/Input.hpp b/include/emp/web/Input.hpp
@@ -131,6 +131,7 @@ namespace web {
             function modifyInputs() {
 
                 var input_el = document.getElementById(UTF8ToString($0));
+                if (!input_el) return;
                 input_el.addEventListener("input", modifyOffset);
                 // the following taken from http://stackoverflow.com/questions/2856513/trigger-onchange-event-manually
                 if ("fireEvent" in input_el) {

diff --git a/include/emp/web/Listeners.hpp b/include/emp/web/Listeners.hpp
@@ -113,7 +113,8 @@ namespace web {
         MAIN_THREAD_EM_ASM({
           var id = UTF8ToString($0);
           var name = UTF8ToString($1);
-          document.getElementById(id).addEventListener(name, function(evt) {
+          var element = document.getElementById(id);
+          if (element) element.addEventListener(name, function(evt) {
               emp.Callback($2, evt);
           });
         }, widget_id.c_str(), event_name.c_str(), fun_id);

diff --git a/include/emp/web/Table.hpp b/include/emp/web/Table.hpp
@@ -221,9 +221,11 @@ namespace web {
               parent_id = UTF8ToString($0);
               child_id = UTF8ToString($1);
               let parent = document.getElementById(parent_id);
-              let span = document.createElement('span');
-              span.id = child_id;
-              parent.appendChild(span);
+              if (parent) {
+                let span = document.createElement('span');
+                span.id = child_id;
+                parent.appendChild(span);
+              }
           }, cell_id.c_str(), in.GetID().c_str());
 
           // Now that the new widget has some place to hook in, activate it!

diff --git a/include/emp/web/TextFeed.hpp b/include/emp/web/TextFeed.hpp
@@ -135,7 +135,7 @@ namespace web {
       MAIN_THREAD_ASYNC_EM_ASM({
         var elementId = UTF8ToString($0);  // Convert UTF-8 encoded string to JavaScript string
         var targetElement = document.getElementById(elementId);
-        targetElement.removeChild(targetElement.firstChild);
+        if (targetElement) targetElement.removeChild(targetElement.firstChild);
       }, id.c_str() );
 
     }

diff --git a/include/emp/web/Widget.hpp b/include/emp/web/Widget.hpp
@@ -384,7 +384,8 @@ namespace web {
         MAIN_THREAD_EM_ASM({
             var widget_id = UTF8ToString($0);
             var out_html = UTF8ToString($1);
-            document.getElementById(widget_id).outerHTML = out_html;
+            var element = document.getElementById(widget_id);
+            if (element) element.outerHTML = out_html;
           }, id.c_str(), ss.str().c_str());
 
         // If active update style, trigger JS, and recurse to children!
@@ -498,15 +499,19 @@ namespace web {
     emp_assert(GetID() != "");  // Must have a name!
     return MAIN_THREAD_EM_ASM_DOUBLE({
       var id = UTF8ToString($0);
-      return document.getElementById(id).clientWidth;
+      var element = document.getElementById(id);
+      if (!element) return -1.0; // Check if element exists
+      return element.clientWidth;
     }, GetID().c_str());
   }
   double Widget::GetHeight(){
     if (!info) return -1.0;
     emp_assert(GetID() != "");  // Must have a name!
     return MAIN_THREAD_EM_ASM_DOUBLE({
       var id = UTF8ToString($0);
-      return document.getElementById(id).clientHeight;
+      var element = document.getElementById(id);
+      if (!element) return -1.0; // Check if element exists
+      return element.clientHeight;
     }, GetID().c_str());
   }
   double Widget::GetInnerWidth(){
@@ -544,15 +549,19 @@ namespace web {
     emp_assert(GetID() != "");  // Must have a name!
     return MAIN_THREAD_EM_ASM_DOUBLE({
       var id = UTF8ToString($0);
-      return document.getElementById(id).offsetWidth;
+      var element = document.getElementById(id);
+      if (!element) return 0.0; // Check if element exists
+      return element.offsetWidth;
     }, GetID().c_str());
   }
   double Widget::GetOuterHeight(){
     if (!info) return -1.0;
     emp_assert(GetID() != "");  // Must have a name!
     return MAIN_THREAD_EM_ASM_DOUBLE({
       var id = UTF8ToString($0);
-      return document.getElementById(id).offsetHeight;
+      var element = document.getElementById(id);
+      if (!element) return 0.0; // Check if element exists
+      return element.offsetHeight;
     }, GetID().c_str());
   }