blobify pdfs, may help on bad browsers

static/js/markdown.js

@@ -89,6 +89,56 @@ const svgChangeTheme = (mode) => {
   }
 };
 
+/**
+ * Replace base64 urls of embeded PDFs into blob
+ */
+const blobifyPdfs = () => {
+  const pdfContentType = "application/pdf";
+  for (const item of document.getElementsByTagName("embed")) {
+    if (!item.src.startsWith(`data:${pdfContentType};base64,`)) {
+      // Exclude embed who are not PDFs encoded via base64
+      continue;
+    }
+
+    /**
+     * Convert Base64 data to a blob
+     * @param {String} b64Data Encoded data
+     * @param {Number} sliceSize Size of the slices
+     * @returns Blob representing the data
+     */
+    const base64ToBlob = async (b64Data, sliceSize = 512) => {
+      const byteCharacters = atob(b64Data);
+      const byteArrays = [];
+      for (
+        let offset = 0;
+        offset < byteCharacters.length;
+        offset += sliceSize
+      ) {
+        const slice = byteCharacters.slice(offset, offset + sliceSize);
+
+        const byteNumbers = new Array(slice.length);
+        for (let i = 0; i < slice.length; i++) {
+          byteNumbers[i] = slice.charCodeAt(i);
+        }
+
+        const byteArray = new Uint8Array(byteNumbers);
+        byteArrays.push(byteArray);
+      }
+
+      return new Blob(byteArrays, { type: pdfContentType });
+    };
+
+    base64ToBlob(item.src.split(",")[1]).then((blob) => {
+      item.src = URL.createObjectURL(blob);
+    });
+  }
+};
+
+window.addEventListener("DOMContentLoaded", () => {
+  // Turn Base64 PDFs into blobs
+  blobifyPdfs();
+});
+
 window.addEventListener("load", () => {
   // Fix SVG images
   svgChangeTheme(