Fix: Older versions of webkit iOS incorrectly cache range requests

src/lib/util.js

@@ -570,6 +570,7 @@ export function replacePlaceholders(string, placeholderValues) {
         /* eslint-enable no-plusplus */
     });
 }
+
 /**
  * Check to see if a file requires a Box3D viewer to be viewed
  *

src/lib/viewers/doc/DocBaseViewer.js

@@ -511,6 +511,8 @@ class DocBaseViewer extends BaseViewer {
      * @return {Promise} Promise to initialize Viewer
      */
     initViewer(pdfUrl) {
+        this.bindDOMListeners();
+
         // Initialize PDF.js in container
         this.pdfViewer = new PDFJS.PDFViewer({
             container: this.docEl,
@@ -531,15 +533,22 @@ class DocBaseViewer extends BaseViewer {
                 RANGE_REQUEST_CHUNK_SIZE_NON_US;
         }
 
-        this.bindDOMListeners();
-
-        // Load PDF from representation URL
-        this.pdfLoadingTask = PDFJS.getDocument({
+        const docInitParams = {
             url: pdfUrl,
             rangeChunkSize
-        });
+        };
+
+        // Fix incorrectly cached range requests on older versions of iOS webkit browsers,
+        // see: https://bugs.webkit.org/show_bug.cgi?id=82672
+        if (this.isMobile && Browser.isIOS()) {
+            docInitParams.httpHeaders = {
+                'If-None-Match': 'webkit-no-cache'
+            };
+        }
 
-        // Set document for PDF.js
+        // Load PDF from representation URL and set as document for pdf.js. Cache
+        // the loading task so we can cancel if needed
+        this.pdfLoadingTask = PDFJS.getDocument(docInitParams);
         return this.pdfLoadingTask.then((doc) => {
             this.pdfViewer.setDocument(doc);
 

src/lib/viewers/doc/__tests__/DocBaseViewer-test.js

@@ -834,6 +834,25 @@ describe('src/lib/viewers/doc/DocBaseViewer', () => {
             });
         });
 
+        it('should set a cache-busting header if on mobile', () => {
+            docBase.options.location = {
+                locale: 'en-US'
+            };
+            docBase.isMobile = true;
+            sandbox.stub(Browser, 'isIOS').returns(true);
+            sandbox.stub(PDFJS, 'getDocument').returns(Promise.resolve({}));
+
+            return docBase.initViewer('').then(() => {
+                expect(PDFJS.getDocument).to.be.calledWith({
+                    url: '',
+                    rangeChunkSize: 1048576,
+                    httpHeaders: {
+                        'If-None-Match': 'webkit-no-cache'
+                    }
+                });
+            });
+        });
+
         it('should resolve the loading task and set the document/viewer', () => {
             const doc = {
                 url: 'url'