From 133a073ef78ac33a77d873f2597a7fb3d07ff663 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 19 May 2017 09:51:17 +0530
Subject: [PATCH] Refuse to work at all on browsers that do not support <iframe
 srcdoc>

---
 src/pyj/book_list/main.pyj | 6 ++++++
 src/pyj/utils.pyj          | 4 +++-
 2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/src/pyj/book_list/main.pyj b/src/pyj/book_list/main.pyj
index 9e83e5653f..aa303ebac8 100644
--- a/src/pyj/book_list/main.pyj
+++ b/src/pyj/book_list/main.pyj
@@ -125,6 +125,12 @@ def do_update_interface_data():
 
 
 def main():
+    if document.createElement('iframe').srcdoc is undefined:
+        document.body.innerHTML = '<p style="margin:1.5em; max-width: 40em">' + _(
+            'You are using a browser that does not have the iframe srcdoc attribute.'
+        ' This is not supported. Use a better browser such as <b>Google Chrome</b> or <b>Mozilla'
+        ' Firefox</b>, instead.')
+        return
     interface_data = get_interface_data()
     if interface_data.is_default or not interface_data.library_map:
         load_interface_data()
diff --git a/src/pyj/utils.pyj b/src/pyj/utils.pyj
index 1f6ddf1ab3..dad3172d6d 100644
--- a/src/pyj/utils.pyj
+++ b/src/pyj/utils.pyj
@@ -231,7 +231,9 @@ def sandboxed_html(html, style, sandbox):
     html = html or ''
     css = 'html, body { margin: 0; padding: 0; font-family: __FONT__ } p:first-child { margin-top: 0; padding-top: 0; -webkit-margin-before: 0 }'.replace('__FONT__', get_font_family())
     css += style or ''
-    ans.srcdoc = f'<html><head><style>{css}</style></head><body>{html}</body></html>'
+    final_html = f'<!DOCTYPE html><html><head><style>{css}</style></head><body>{html}</body></html>'
+    # Microsoft Edge does not support srcdoc not does it work using a data URI.
+    ans.srcdoc = final_html
     return ans
 
 if __name__ is '__main__':
