diff --git a/examples/learning/prevnext.html b/examples/learning/prevnext.html
index 40c1488c8..e1043bf1e 100644
--- a/examples/learning/prevnext.html
+++ b/examples/learning/prevnext.html
@@ -9,8 +9,8 @@
 <h1>'Previous/Next' example</h1>
 
 <div>
-  <button id="prev">Previous</button>
-  <button id="next">Next</button>
+  <button id="prev" type="button">Previous</button>
+  <button id="next" type="button">Next</button>
   &nbsp; &nbsp;
   <span>Page: <span id="page_num"></span> / <span id="page_count"></span></span>
 </div>
diff --git a/examples/mobile-viewer/viewer.html b/examples/mobile-viewer/viewer.html
index 50bbfd781..6bd8b5406 100644
--- a/examples/mobile-viewer/viewer.html
+++ b/examples/mobile-viewer/viewer.html
@@ -43,13 +43,13 @@ limitations under the License.
     </div>
 
     <footer>
-      <button class="toolbarButton pageUp" title="Previous Page" id="previous"></button>
-      <button class="toolbarButton pageDown" title="Next Page" id="next"></button>
+      <button class="toolbarButton pageUp" title="Previous Page" id="previous" type="button"></button>
+      <button class="toolbarButton pageDown" title="Next Page" id="next" type="button"></button>
 
       <input type="number" id="pageNumber" class="toolbarField pageNumber" value="1" size="4" min="1">
 
-      <button class="toolbarButton zoomOut" title="Zoom Out" id="zoomOut"></button>
-      <button class="toolbarButton zoomIn" title="Zoom In" id="zoomIn"></button>
+      <button class="toolbarButton zoomOut" title="Zoom Out" id="zoomOut" type="button"></button>
+      <button class="toolbarButton zoomIn" title="Zoom In" id="zoomIn" type="button"></button>
     </footer>
 
      <script src="viewer.mjs" type="module"></script>
diff --git a/extensions/chromium/options/options.html b/extensions/chromium/options/options.html
index 8d5661fcb..78385926f 100644
--- a/extensions/chromium/options/options.html
+++ b/extensions/chromium/options/options.html
@@ -31,7 +31,7 @@ body {
 </head>
 <body>
 <div id="settings-boxes"></div>
-<button id="reset-button">Restore default settings</button>
+<button id="reset-button" type="button">Restore default settings</button>
 
 <template id="checkbox-template">
 <!-- Chromium's style: //src/extensions/renderer/resources/extension.css -->
diff --git a/web/viewer-geckoview.html b/web/viewer-geckoview.html
index 44e2bd8ed..fe3e2583e 100644
--- a/web/viewer-geckoview.html
+++ b/web/viewer-geckoview.html
@@ -99,7 +99,7 @@ See https://github.com/adobe-type-tools/cmap-resources
       <div id="mainContainer">
 
         <div id="floatingToolbar">
-          <button id="download" class="toolbarButton" title="Download" tabindex="31" data-l10n-id="pdfjs-download-button">
+          <button id="download" class="toolbarButton" type="button" title="Download" tabindex="31" data-l10n-id="pdfjs-download-button">
             <span data-l10n-id="pdfjs-download-button-label">Download</span>
           </button>
         </div>
@@ -118,8 +118,8 @@ See https://github.com/adobe-type-tools/cmap-resources
             <input type="password" id="password" class="toolbarField">
           </div>
           <div class="buttonRow">
-            <button id="passwordCancel" class="dialogButton"><span data-l10n-id="pdfjs-password-cancel-button">Cancel</span></button>
-            <button id="passwordSubmit" class="dialogButton"><span data-l10n-id="pdfjs-password-ok-button">OK</span></button>
+            <button id="passwordCancel" class="dialogButton" type="button"><span data-l10n-id="pdfjs-password-cancel-button">Cancel</span></button>
+            <button id="passwordSubmit" class="dialogButton" type="button"><span data-l10n-id="pdfjs-password-ok-button">OK</span></button>
           </div>
         </dialog>
       </div>  <!-- dialogContainer -->
diff --git a/web/viewer.html b/web/viewer.html
index 3a31cf846..ab8de7476 100644
--- a/web/viewer.html
+++ b/web/viewer.html
@@ -100,16 +100,16 @@ See https://github.com/adobe-type-tools/cmap-resources
         <div id="toolbarSidebar">
           <div id="toolbarSidebarLeft">
             <div id="sidebarViewButtons" class="splitToolbarButton toggled" role="radiogroup">
-              <button id="viewThumbnail" class="toolbarButton toggled" title="Show Thumbnails" tabindex="2" data-l10n-id="pdfjs-thumbs-button" role="radio" aria-checked="true" aria-controls="thumbnailView">
+              <button id="viewThumbnail" class="toolbarButton toggled" type="button" title="Show Thumbnails" tabindex="2" data-l10n-id="pdfjs-thumbs-button" role="radio" aria-checked="true" aria-controls="thumbnailView">
                  <span data-l10n-id="pdfjs-thumbs-button-label">Thumbnails</span>
               </button>
-              <button id="viewOutline" class="toolbarButton" title="Show Document Outline (double-click to expand/collapse all items)" tabindex="3" data-l10n-id="pdfjs-document-outline-button" role="radio" aria-checked="false" aria-controls="outlineView">
+              <button id="viewOutline" class="toolbarButton" type="button" title="Show Document Outline (double-click to expand/collapse all items)" tabindex="3" data-l10n-id="pdfjs-document-outline-button" role="radio" aria-checked="false" aria-controls="outlineView">
                  <span data-l10n-id="pdfjs-document-outline-button-label">Document Outline</span>
               </button>
-              <button id="viewAttachments" class="toolbarButton" title="Show Attachments" tabindex="4" data-l10n-id="pdfjs-attachments-button" role="radio" aria-checked="false" aria-controls="attachmentsView">
+              <button id="viewAttachments" class="toolbarButton" type="button" title="Show Attachments" tabindex="4" data-l10n-id="pdfjs-attachments-button" role="radio" aria-checked="false" aria-controls="attachmentsView">
                  <span data-l10n-id="pdfjs-attachments-button-label">Attachments</span>
               </button>
-              <button id="viewLayers" class="toolbarButton" title="Show Layers (double-click to reset all layers to the default state)" tabindex="5" data-l10n-id="pdfjs-layers-button" role="radio" aria-checked="false" aria-controls="layersView">
+              <button id="viewLayers" class="toolbarButton" type="button" title="Show Layers (double-click to reset all layers to the default state)" tabindex="5" data-l10n-id="pdfjs-layers-button" role="radio" aria-checked="false" aria-controls="layersView">
                  <span data-l10n-id="pdfjs-layers-button-label">Layers</span>
               </button>
             </div>
@@ -119,7 +119,7 @@ See https://github.com/adobe-type-tools/cmap-resources
             <div id="outlineOptionsContainer">
               <div class="verticalToolbarSeparator"></div>
 
-              <button id="currentOutlineItem" class="toolbarButton" disabled="disabled" title="Find Current Outline Item" tabindex="6" data-l10n-id="pdfjs-current-outline-item-button">
+              <button id="currentOutlineItem" class="toolbarButton" type="button" disabled="disabled" title="Find Current Outline Item" tabindex="6" data-l10n-id="pdfjs-current-outline-item-button">
                 <span data-l10n-id="pdfjs-current-outline-item-button-label">Current Outline Item</span>
               </button>
             </div>
@@ -145,11 +145,11 @@ See https://github.com/adobe-type-tools/cmap-resources
               <input id="findInput" class="toolbarField" title="Find" placeholder="Find in document…" tabindex="91" data-l10n-id="pdfjs-find-input" aria-invalid="false">
             </span>
             <div class="splitToolbarButton">
-              <button id="findPrevious" class="toolbarButton" title="Find the previous occurrence of the phrase" tabindex="92" data-l10n-id="pdfjs-find-previous-button">
+              <button id="findPrevious" class="toolbarButton" type="button" title="Find the previous occurrence of the phrase" tabindex="92" data-l10n-id="pdfjs-find-previous-button">
                 <span data-l10n-id="pdfjs-find-previous-button-label">Previous</span>
               </button>
               <div class="splitToolbarButtonSeparator"></div>
-              <button id="findNext" class="toolbarButton" title="Find the next occurrence of the phrase" tabindex="93" data-l10n-id="pdfjs-find-next-button">
+              <button id="findNext" class="toolbarButton" type="button" title="Find the next occurrence of the phrase" tabindex="93" data-l10n-id="pdfjs-find-next-button">
                 <span data-l10n-id="pdfjs-find-next-button-label">Next</span>
               </button>
             </div>
@@ -189,7 +189,7 @@ See https://github.com/adobe-type-tools/cmap-resources
               <div class="divider"></div>
               <div class="toggler">
                 <label for="editorHighlightShowAll" class="editorParamsLabel" data-l10n-id="pdfjs-editor-highlight-show-all-button-label">Show all</label>
-                <button id="editorHighlightShowAll" class="toggle-button" data-l10n-id="pdfjs-editor-highlight-show-all-button" aria-pressed="true" tabindex="102"></button>
+                <button id="editorHighlightShowAll" class="toggle-button" type="button" data-l10n-id="pdfjs-editor-highlight-show-all-button" aria-pressed="true" tabindex="102"></button>
               </div>
             </div>
           </div>
@@ -227,7 +227,7 @@ See https://github.com/adobe-type-tools/cmap-resources
 
         <div class="editorParamsToolbar hidden doorHangerRight" id="editorStampParamsToolbar">
           <div class="editorParamsToolbarContainer">
-            <button id="editorStampAddImage" class="secondaryToolbarButton" title="Add image" tabindex="108" data-l10n-id="pdfjs-editor-stamp-add-image-button">
+            <button id="editorStampAddImage" class="secondaryToolbarButton" type="button" title="Add image" tabindex="108" data-l10n-id="pdfjs-editor-stamp-add-image-button">
               <span class="editorParamsLabel" data-l10n-id="pdfjs-editor-stamp-add-image-button-label">Add image</span>
             </button>
           </div>
@@ -236,16 +236,16 @@ See https://github.com/adobe-type-tools/cmap-resources
         <div id="secondaryToolbar" class="secondaryToolbar hidden doorHangerRight">
           <div id="secondaryToolbarButtonContainer">
 <!--#if GENERIC-->
-            <button id="secondaryOpenFile" class="secondaryToolbarButton" title="Open File" tabindex="51" data-l10n-id="pdfjs-open-file-button">
+            <button id="secondaryOpenFile" class="secondaryToolbarButton" type="button" title="Open File" tabindex="51" data-l10n-id="pdfjs-open-file-button">
               <span data-l10n-id="pdfjs-open-file-button-label">Open</span>
             </button>
 <!--#endif-->
 
-            <button id="secondaryPrint" class="secondaryToolbarButton visibleMediumView" title="Print" tabindex="52" data-l10n-id="pdfjs-print-button">
+            <button id="secondaryPrint" class="secondaryToolbarButton visibleMediumView" type="button" title="Print" tabindex="52" data-l10n-id="pdfjs-print-button">
               <span data-l10n-id="pdfjs-print-button-label">Print</span>
             </button>
 
-            <button id="secondaryDownload" class="secondaryToolbarButton visibleMediumView" title="Save" tabindex="53" data-l10n-id="pdfjs-save-button">
+            <button id="secondaryDownload" class="secondaryToolbarButton visibleMediumView" type="button" title="Save" tabindex="53" data-l10n-id="pdfjs-save-button">
               <span data-l10n-id="pdfjs-save-button-label">Save</span>
             </button>
 
@@ -255,7 +255,7 @@ See https://github.com/adobe-type-tools/cmap-resources
 <!--        <div class="horizontalToolbarSeparator visibleMediumView"></div>-->
 <!--#endif-->
 
-            <button id="presentationMode" class="secondaryToolbarButton" title="Switch to Presentation Mode" tabindex="54" data-l10n-id="pdfjs-presentation-mode-button">
+            <button id="presentationMode" class="secondaryToolbarButton" type="button" title="Switch to Presentation Mode" tabindex="54" data-l10n-id="pdfjs-presentation-mode-button">
               <span data-l10n-id="pdfjs-presentation-mode-button-label">Presentation Mode</span>
             </button>
 
@@ -265,29 +265,29 @@ See https://github.com/adobe-type-tools/cmap-resources
 
             <div id="viewBookmarkSeparator" class="horizontalToolbarSeparator"></div>
 
-            <button id="firstPage" class="secondaryToolbarButton" title="Go to First Page" tabindex="56" data-l10n-id="pdfjs-first-page-button">
+            <button id="firstPage" class="secondaryToolbarButton" type="button" title="Go to First Page" tabindex="56" data-l10n-id="pdfjs-first-page-button">
               <span data-l10n-id="pdfjs-first-page-button-label">Go to First Page</span>
             </button>
-            <button id="lastPage" class="secondaryToolbarButton" title="Go to Last Page" tabindex="57" data-l10n-id="pdfjs-last-page-button">
+            <button id="lastPage" class="secondaryToolbarButton" type="button" title="Go to Last Page" tabindex="57" data-l10n-id="pdfjs-last-page-button">
               <span data-l10n-id="pdfjs-last-page-button-label">Go to Last Page</span>
             </button>
 
             <div class="horizontalToolbarSeparator"></div>
 
-            <button id="pageRotateCw" class="secondaryToolbarButton" title="Rotate Clockwise" tabindex="58" data-l10n-id="pdfjs-page-rotate-cw-button">
+            <button id="pageRotateCw" class="secondaryToolbarButton" type="button" title="Rotate Clockwise" tabindex="58" data-l10n-id="pdfjs-page-rotate-cw-button">
               <span data-l10n-id="pdfjs-page-rotate-cw-button-label">Rotate Clockwise</span>
             </button>
-            <button id="pageRotateCcw" class="secondaryToolbarButton" title="Rotate Counterclockwise" tabindex="59" data-l10n-id="pdfjs-page-rotate-ccw-button">
+            <button id="pageRotateCcw" class="secondaryToolbarButton" type="button" title="Rotate Counterclockwise" tabindex="59" data-l10n-id="pdfjs-page-rotate-ccw-button">
               <span data-l10n-id="pdfjs-page-rotate-ccw-button-label">Rotate Counterclockwise</span>
             </button>
 
             <div class="horizontalToolbarSeparator"></div>
 
             <div id="cursorToolButtons" role="radiogroup">
-              <button id="cursorSelectTool" class="secondaryToolbarButton toggled" title="Enable Text Selection Tool" tabindex="60" data-l10n-id="pdfjs-cursor-text-select-tool-button" role="radio" aria-checked="true">
+              <button id="cursorSelectTool" class="secondaryToolbarButton toggled" type="button" title="Enable Text Selection Tool" tabindex="60" data-l10n-id="pdfjs-cursor-text-select-tool-button" role="radio" aria-checked="true">
                 <span data-l10n-id="pdfjs-cursor-text-select-tool-button-label">Text Selection Tool</span>
               </button>
-              <button id="cursorHandTool" class="secondaryToolbarButton" title="Enable Hand Tool" tabindex="61" data-l10n-id="pdfjs-cursor-hand-tool-button" role="radio" aria-checked="false">
+              <button id="cursorHandTool" class="secondaryToolbarButton" type="button" title="Enable Hand Tool" tabindex="61" data-l10n-id="pdfjs-cursor-hand-tool-button" role="radio" aria-checked="false">
                 <span data-l10n-id="pdfjs-cursor-hand-tool-button-label">Hand Tool</span>
               </button>
             </div>
@@ -295,16 +295,16 @@ See https://github.com/adobe-type-tools/cmap-resources
             <div class="horizontalToolbarSeparator"></div>
 
             <div id="scrollModeButtons" role="radiogroup">
-              <button id="scrollPage" class="secondaryToolbarButton" title="Use Page Scrolling" tabindex="62" data-l10n-id="pdfjs-scroll-page-button" role="radio" aria-checked="false">
+              <button id="scrollPage" class="secondaryToolbarButton" type="button" title="Use Page Scrolling" tabindex="62" data-l10n-id="pdfjs-scroll-page-button" role="radio" aria-checked="false">
                 <span data-l10n-id="pdfjs-scroll-page-button-label">Page Scrolling</span>
               </button>
-              <button id="scrollVertical" class="secondaryToolbarButton toggled" title="Use Vertical Scrolling" tabindex="63" data-l10n-id="pdfjs-scroll-vertical-button" role="radio" aria-checked="true">
+              <button id="scrollVertical" class="secondaryToolbarButton toggled" type="button" title="Use Vertical Scrolling" tabindex="63" data-l10n-id="pdfjs-scroll-vertical-button" role="radio" aria-checked="true">
                 <span data-l10n-id="pdfjs-scroll-vertical-button-label" >Vertical Scrolling</span>
               </button>
-              <button id="scrollHorizontal" class="secondaryToolbarButton" title="Use Horizontal Scrolling" tabindex="64" data-l10n-id="pdfjs-scroll-horizontal-button" role="radio" aria-checked="false">
+              <button id="scrollHorizontal" class="secondaryToolbarButton" type="button" title="Use Horizontal Scrolling" tabindex="64" data-l10n-id="pdfjs-scroll-horizontal-button" role="radio" aria-checked="false">
                 <span data-l10n-id="pdfjs-scroll-horizontal-button-label">Horizontal Scrolling</span>
               </button>
-              <button id="scrollWrapped" class="secondaryToolbarButton" title="Use Wrapped Scrolling" tabindex="65" data-l10n-id="pdfjs-scroll-wrapped-button" role="radio" aria-checked="false">
+              <button id="scrollWrapped" class="secondaryToolbarButton" type="button" title="Use Wrapped Scrolling" tabindex="65" data-l10n-id="pdfjs-scroll-wrapped-button" role="radio" aria-checked="false">
                 <span data-l10n-id="pdfjs-scroll-wrapped-button-label">Wrapped Scrolling</span>
               </button>
             </div>
@@ -312,20 +312,20 @@ See https://github.com/adobe-type-tools/cmap-resources
             <div class="horizontalToolbarSeparator"></div>
 
             <div id="spreadModeButtons" role="radiogroup">
-              <button id="spreadNone" class="secondaryToolbarButton toggled" title="Do not join page spreads" tabindex="66" data-l10n-id="pdfjs-spread-none-button" role="radio" aria-checked="true">
+              <button id="spreadNone" class="secondaryToolbarButton toggled" type="button" title="Do not join page spreads" tabindex="66" data-l10n-id="pdfjs-spread-none-button" role="radio" aria-checked="true">
                 <span data-l10n-id="pdfjs-spread-none-button-label">No Spreads</span>
               </button>
-              <button id="spreadOdd" class="secondaryToolbarButton" title="Join page spreads starting with odd-numbered pages" tabindex="67" data-l10n-id="pdfjs-spread-odd-button" role="radio" aria-checked="false">
+              <button id="spreadOdd" class="secondaryToolbarButton" type="button" title="Join page spreads starting with odd-numbered pages" tabindex="67" data-l10n-id="pdfjs-spread-odd-button" role="radio" aria-checked="false">
                 <span data-l10n-id="pdfjs-spread-odd-button-label">Odd Spreads</span>
               </button>
-              <button id="spreadEven" class="secondaryToolbarButton" title="Join page spreads starting with even-numbered pages" tabindex="68" data-l10n-id="pdfjs-spread-even-button" role="radio" aria-checked="false">
+              <button id="spreadEven" class="secondaryToolbarButton" type="button" title="Join page spreads starting with even-numbered pages" tabindex="68" data-l10n-id="pdfjs-spread-even-button" role="radio" aria-checked="false">
                 <span data-l10n-id="pdfjs-spread-even-button-label">Even Spreads</span>
               </button>
             </div>
 
             <div class="horizontalToolbarSeparator"></div>
 
-            <button id="documentProperties" class="secondaryToolbarButton" title="Document Properties…" tabindex="69" data-l10n-id="pdfjs-document-properties-button" aria-controls="documentPropertiesDialog">
+            <button id="documentProperties" class="secondaryToolbarButton" type="button" title="Document Properties…" tabindex="69" data-l10n-id="pdfjs-document-properties-button" aria-controls="documentPropertiesDialog">
               <span data-l10n-id="pdfjs-document-properties-button-label">Document Properties…</span>
             </button>
           </div>
@@ -335,19 +335,19 @@ See https://github.com/adobe-type-tools/cmap-resources
           <div id="toolbarContainer">
             <div id="toolbarViewer">
               <div id="toolbarViewerLeft">
-                <button id="sidebarToggle" class="toolbarButton" title="Toggle Sidebar" tabindex="11" data-l10n-id="pdfjs-toggle-sidebar-button" aria-expanded="false" aria-controls="sidebarContainer">
+                <button id="sidebarToggle" class="toolbarButton" type="button" title="Toggle Sidebar" tabindex="11" data-l10n-id="pdfjs-toggle-sidebar-button" aria-expanded="false" aria-controls="sidebarContainer">
                   <span data-l10n-id="pdfjs-toggle-sidebar-button-label">Toggle Sidebar</span>
                 </button>
                 <div class="toolbarButtonSpacer"></div>
-                <button id="viewFind" class="toolbarButton" title="Find in Document" tabindex="12" data-l10n-id="pdfjs-findbar-button" aria-expanded="false" aria-controls="findbar">
+                <button id="viewFind" class="toolbarButton" type="button" title="Find in Document" tabindex="12" data-l10n-id="pdfjs-findbar-button" aria-expanded="false" aria-controls="findbar">
                   <span data-l10n-id="pdfjs-findbar-button-label">Find</span>
                 </button>
                 <div class="splitToolbarButton hiddenSmallView">
-                  <button class="toolbarButton" title="Previous Page" id="previous" tabindex="13" data-l10n-id="pdfjs-previous-button">
+                  <button class="toolbarButton" title="Previous Page" id="previous" type="button" tabindex="13" data-l10n-id="pdfjs-previous-button">
                     <span data-l10n-id="pdfjs-previous-button-label">Previous</span>
                   </button>
                   <div class="splitToolbarButtonSeparator"></div>
-                  <button class="toolbarButton" title="Next Page" id="next" tabindex="14" data-l10n-id="pdfjs-next-button">
+                  <button class="toolbarButton" title="Next Page" id="next" type="button" tabindex="14" data-l10n-id="pdfjs-next-button">
                     <span data-l10n-id="pdfjs-next-button-label">Next</span>
                   </button>
                 </div>
@@ -358,43 +358,43 @@ See https://github.com/adobe-type-tools/cmap-resources
               </div>
               <div id="toolbarViewerRight">
                 <div id="editorModeButtons" class="splitToolbarButton toggled" role="radiogroup">
-                  <button id="editorHighlight" class="toolbarButton" hidden="true" disabled="disabled" title="Highlight" role="radio" aria-checked="false" aria-controls="editorHighlightParamsToolbar" tabindex="31" data-l10n-id="pdfjs-editor-highlight-button">
+                  <button id="editorHighlight" class="toolbarButton" type="button" hidden="true" disabled="disabled" title="Highlight" role="radio" aria-checked="false" aria-controls="editorHighlightParamsToolbar" tabindex="31" data-l10n-id="pdfjs-editor-highlight-button">
                     <span data-l10n-id="pdfjs-editor-highlight-button-label">Highlight</span>
                   </button>
-                  <button id="editorFreeText" class="toolbarButton" disabled="disabled" title="Text" role="radio" aria-checked="false" aria-controls="editorFreeTextParamsToolbar" tabindex="32" data-l10n-id="pdfjs-editor-free-text-button">
+                  <button id="editorFreeText" class="toolbarButton" type="button" disabled="disabled" title="Text" role="radio" aria-checked="false" aria-controls="editorFreeTextParamsToolbar" tabindex="32" data-l10n-id="pdfjs-editor-free-text-button">
                     <span data-l10n-id="pdfjs-editor-free-text-button-label">Text</span>
                   </button>
-                  <button id="editorInk" class="toolbarButton" disabled="disabled" title="Draw" role="radio" aria-checked="false" aria-controls="editorInkParamsToolbar" tabindex="33" data-l10n-id="pdfjs-editor-ink-button">
+                  <button id="editorInk" class="toolbarButton" type="button" disabled="disabled" title="Draw" role="radio" aria-checked="false" aria-controls="editorInkParamsToolbar" tabindex="33" data-l10n-id="pdfjs-editor-ink-button">
                     <span data-l10n-id="pdfjs-editor-ink-button-label">Draw</span>
                   </button>
-                  <button id="editorStamp" class="toolbarButton" disabled="disabled" title="Add or edit images" role="radio" aria-checked="false" aria-controls="editorStampParamsToolbar" tabindex="34" data-l10n-id="pdfjs-editor-stamp-button">
+                  <button id="editorStamp" class="toolbarButton" type="button" disabled="disabled" title="Add or edit images" role="radio" aria-checked="false" aria-controls="editorStampParamsToolbar" tabindex="34" data-l10n-id="pdfjs-editor-stamp-button">
                     <span data-l10n-id="pdfjs-editor-stamp-button-label">Add or edit images</span>
                   </button>
                 </div>
 
                 <div id="editorModeSeparator" class="verticalToolbarSeparator"></div>
 
-                <button id="print" class="toolbarButton hiddenMediumView" title="Print" tabindex="41" data-l10n-id="pdfjs-print-button">
+                <button id="print" class="toolbarButton hiddenMediumView" type="button" title="Print" tabindex="41" data-l10n-id="pdfjs-print-button">
                   <span data-l10n-id="pdfjs-print-button-label">Print</span>
                 </button>
 
-                <button id="download" class="toolbarButton hiddenMediumView" title="Save" tabindex="42" data-l10n-id="pdfjs-save-button">
+                <button id="download" class="toolbarButton hiddenMediumView" type="button" title="Save" tabindex="42" data-l10n-id="pdfjs-save-button">
                   <span data-l10n-id="pdfjs-save-button-label">Save</span>
                 </button>
 
                 <div class="verticalToolbarSeparator hiddenMediumView"></div>
 
-                <button id="secondaryToolbarToggle" class="toolbarButton" title="Tools" tabindex="43" data-l10n-id="pdfjs-tools-button" aria-expanded="false" aria-controls="secondaryToolbar">
+                <button id="secondaryToolbarToggle" class="toolbarButton" type="button" title="Tools" tabindex="43" data-l10n-id="pdfjs-tools-button" aria-expanded="false" aria-controls="secondaryToolbar">
                   <span data-l10n-id="pdfjs-tools-button-label">Tools</span>
                 </button>
               </div>
               <div id="toolbarViewerMiddle">
                 <div class="splitToolbarButton">
-                  <button id="zoomOut" class="toolbarButton" title="Zoom Out" tabindex="21" data-l10n-id="pdfjs-zoom-out-button">
+                  <button id="zoomOut" class="toolbarButton" type="button" title="Zoom Out" tabindex="21" data-l10n-id="pdfjs-zoom-out-button">
                     <span data-l10n-id="pdfjs-zoom-out-button-label">Zoom Out</span>
                   </button>
                   <div class="splitToolbarButtonSeparator"></div>
-                  <button id="zoomIn" class="toolbarButton" title="Zoom In" tabindex="22" data-l10n-id="pdfjs-zoom-in-button">
+                  <button id="zoomIn" class="toolbarButton" type="button" title="Zoom In" tabindex="22" data-l10n-id="pdfjs-zoom-in-button">
                     <span data-l10n-id="pdfjs-zoom-in-button-label">Zoom In</span>
                    </button>
                 </div>
@@ -440,8 +440,8 @@ See https://github.com/adobe-type-tools/cmap-resources
             <input type="password" id="password" class="toolbarField">
           </div>
           <div class="buttonRow">
-            <button id="passwordCancel" class="dialogButton"><span data-l10n-id="pdfjs-password-cancel-button">Cancel</span></button>
-            <button id="passwordSubmit" class="dialogButton"><span data-l10n-id="pdfjs-password-ok-button">OK</span></button>
+            <button id="passwordCancel" class="dialogButton" type="button"><span data-l10n-id="pdfjs-password-cancel-button">Cancel</span></button>
+            <button id="passwordSubmit" class="dialogButton" type="button"><span data-l10n-id="pdfjs-password-ok-button">OK</span></button>
           </div>
         </dialog>
         <dialog id="documentPropertiesDialog">
@@ -505,7 +505,7 @@ See https://github.com/adobe-type-tools/cmap-resources
             <p id="linearizedField" aria-labelledby="linearizedLabel">-</p>
           </div>
           <div class="buttonRow">
-            <button id="documentPropertiesClose" class="dialogButton"><span data-l10n-id="pdfjs-document-properties-close-button">Close</span></button>
+            <button id="documentPropertiesClose" class="dialogButton" type="button"><span data-l10n-id="pdfjs-document-properties-close-button">Close</span></button>
           </div>
         </dialog>
         <dialog class="dialog altText" id="altTextDialog" aria-labelledby="dialogLabel" aria-describedby="dialogDescription">
@@ -546,8 +546,8 @@ See https://github.com/adobe-type-tools/cmap-resources
               </div>
             </div>
             <div id="buttons">
-              <button id="altTextCancel" class="secondaryButton" tabindex="0"><span data-l10n-id="pdfjs-editor-alt-text-cancel-button">Cancel</span></button>
-              <button id="altTextSave" class="primaryButton" tabindex="0"><span data-l10n-id="pdfjs-editor-alt-text-save-button">Save</span></button>
+              <button id="altTextCancel" class="secondaryButton" type="button" tabindex="0"><span data-l10n-id="pdfjs-editor-alt-text-cancel-button">Cancel</span></button>
+              <button id="altTextSave" class="primaryButton" type="button" tabindex="0"><span data-l10n-id="pdfjs-editor-alt-text-save-button">Save</span></button>
             </div>
           </div>
         </dialog>
@@ -567,7 +567,7 @@ See https://github.com/adobe-type-tools/cmap-resources
                   <div id="newAltTextDisclaimer" role="note"><span data-l10n-id="pdfjs-editor-new-alt-text-disclaimer">This alt text was created automatically.</span> <a href="https://support.mozilla.org/en-US/kb/pdf-alt-text" target="_blank" rel="noopener noreferrer" id="newAltTextLearnMore" data-l10n-id="pdfjs-editor-new-alt-text-disclaimer-learn-more-url" tabindex="0">Learn more</a></div>
                 </div>
                 <div id="newAltTextCreateAutomatically" class="toggler">
-                  <button id="newAltTextCreateAutomaticallyButton" class="toggle-button" aria-pressed="true" tabindex="0"></button>
+                  <button id="newAltTextCreateAutomaticallyButton" class="toggle-button" type="button" aria-pressed="true" tabindex="0"></button>
                   <label for="newAltTextCreateAutomaticallyButton" class="togglerLabel" data-l10n-id="pdfjs-editor-new-alt-text-create-automatically-button-label">Create alt text automatically</label>
                 </div>
                 <div id="newAltTextDownloadModel" class="hidden">
@@ -582,7 +582,7 @@ See https://github.com/adobe-type-tools/cmap-resources
                   <span class="title" data-l10n-id="pdfjs-editor-new-alt-text-error-title">Couldn’t create alt text automatically</span>
                   <span  class="description" data-l10n-id="pdfjs-editor-new-alt-text-error-description">Please write your own alt text or try again later.</span>
                 </div>
-                <button id="newAltTextCloseButton" class="closeButton" tabindex="0" title="Close"><span data-l10n-id="pdfjs-editor-new-alt-text-error-close-button">Close</span></button>
+                <button id="newAltTextCloseButton" class="closeButton" type="button" tabindex="0" title="Close"><span data-l10n-id="pdfjs-editor-new-alt-text-error-close-button">Close</span></button>
               </div>
             </div>
             <div id="newAltTextButtons" class="dialogButtonsGroup">
@@ -603,7 +603,7 @@ See https://github.com/adobe-type-tools/cmap-resources
             <span data-l10n-id="pdfjs-print-progress-percent" data-l10n-args='{ "progress": 0 }' class="relative-progress">0%</span>
           </div>
           <div class="buttonRow">
-            <button id="printCancel" class="dialogButton"><span data-l10n-id="pdfjs-print-progress-close-button">Cancel</span></button>
+            <button id="printCancel" class="dialogButton" type="button"><span data-l10n-id="pdfjs-print-progress-close-button">Cancel</span></button>
           </div>
         </dialog>
 <!--#endif-->
