- Imagelib backward compatibility enhancement: Allow `namespace-key` as

alternative to `namespace` so as not to break old SVG-Edit which fail
  at *presence* of `namespace` (fixes #274)
- Forward compatibility enhancement: Once IE9 support may be dropped,
  we may post messages as objects, so don't break if objects received
  (embedded API, xdomain, Imagelib)

CHANGES.md

@@ -31,6 +31,12 @@
 - Fix (Context menus): Avoid showing double shortcuts (#285); add some
   missing ones
 - Fix (Star extension): Minor: Avoid erring if `inradius` is `NaN`
+- Forward compatibility enhancement: Once IE9 support may be dropped,
+  we may post messages as objects, so don't break if objects received
+  (embedded API, xdomain, Imagelib)
+- Imagelib backward compatibility enhancement: Allow `namespace-key` as
+  alternative to `namespace` so as not to break old SVG-Edit which fail
+  at *presence* of `namespace` (fixes #274)
 - Refactoring: Avoid passing unused arguments, setting unused variables,
   and making unnecessary checks; avoid useless call to `createSVGMatrix`
 - Refactoring: Avoid useless assignment (courtesty lgtm)

editor/embedapi.js

@@ -63,11 +63,11 @@ function addCallback (t, {result, error, id: cbid}) {
 function messageListener (e) {
   // We accept and post strings as opposed to objects for the sake of IE9 support; this
   //   will most likely be changed in the future
-  if (typeof e.data !== 'string') {
+  if (!e.data || !['string', 'object'].includes(typeof e.data)) {
     return;
   }
   const {allowedOrigins} = this,
-    data = e.data && JSON.parse(e.data);
+    data = typeof e.data === 'object' ? e.data : JSON.parse(e.data);
   if (!data || typeof data !== 'object' || data.namespace !== 'svg-edit' ||
     e.source !== this.frame.contentWindow ||
     (!allowedOrigins.includes('*') && !allowedOrigins.includes(e.origin))

editor/extensions/ext-imagelib.js

@@ -63,7 +63,7 @@ export default {
 
     // Receive `postMessage` data
     window.addEventListener('message', function ({origin, data: response}) {
-      if (!response || typeof response !== 'string') {
+      if (!response || !['string', 'object'].includes(typeof response)) {
         // Do nothing
         return;
       }
@@ -71,8 +71,14 @@ export default {
         // Todo: This block can be removed (and the above check changed to
         //   insist on an object) if embedAPI moves away from a string to
         //   an object (if IE9 support not needed)
-        response = JSON.parse(response);
-        if (response.namespace !== 'imagelib') {
+        response = typeof response === 'object' ? response : JSON.parse(response);
+        if (response.namespace !== 'imagelib' &&
+          // Allow this alternative per https://github.com/SVG-Edit/svgedit/issues/274
+          //   so that older libraries may post with `namespace-key` and not
+          //   break older SVG-Edit versions which insisted on the *absence*
+          //   of a `namespace` property
+          response['namespace-key'] !== 'imagelib'
+        ) {
           return;
         }
         if (!allowedImageLibOrigins.includes('*') && !allowedImageLibOrigins.includes(origin)) {

editor/extensions/ext-xdomain-messaging.js

@@ -11,10 +11,10 @@ export default {
     try {
       window.addEventListener('message', function (e) {
         // We accept and post strings for the sake of IE9 support
-        if (typeof e.data !== 'string' || e.data.charAt() === '|') {
+        if (!e.data || !['string', 'object'].includes(typeof e.data) || e.data.charAt() === '|') {
           return;
         }
-        const data = JSON.parse(e.data);
+        const data = typeof e.data === 'object' ? e.data : JSON.parse(e.data);
         if (!data || typeof data !== 'object' || data.namespace !== 'svgCanvas') {
           return;
         }