diff --git a/resources/rapydscript/compiler.js.xz b/resources/rapydscript/compiler.js.xz
index 00f9ad252b..185d5e2e1d 100644
Binary files a/resources/rapydscript/compiler.js.xz and b/resources/rapydscript/compiler.js.xz differ
diff --git a/resources/rapydscript/lib/aes.pyj b/resources/rapydscript/lib/aes.pyj
index bb573635c7..666ed42e9b 100644
--- a/resources/rapydscript/lib/aes.pyj
+++ b/resources/rapydscript/lib/aes.pyj
@@ -14,9 +14,8 @@ def string_to_bytes_slow(string):
         return String.fromCharCode('0x' + p1)
     )
     ua = Uint8Array(binstr.length)
-    Array.prototype.forEach.call(binstr, def(ch, i):
+    for i, ch in enumerate(binstr):
         ua[i] = ch.charCodeAt(0)
-    )
     return ua
 
 def as_hex(array, sep=''):
@@ -46,8 +45,8 @@ def bytes_to_string_slow(bytes, offset):
             i += 3
     return ans.join('')
 
-string_to_bytes = string_to_bytes_encoder if type(TextEncoder) is 'function' else string_to_bytes_slow
-bytes_to_string = bytes_to_string_decoder if type(TextDecoder) is 'function' else bytes_to_string_slow
+string_to_bytes = string_to_bytes_encoder if jstype(TextEncoder) is 'function' else string_to_bytes_slow
+bytes_to_string = bytes_to_string_decoder if jstype(TextDecoder) is 'function' else bytes_to_string_slow
 
 def increment_counter(c):
     # c must be a Uint8Array of length 16
@@ -269,7 +268,7 @@ def random_bytes_secure(sz):
     crypto.getRandomValues(ans)
     return ans
 
-random_bytes = random_bytes_secure if type(crypto) is not 'undefined' and type(crypto.getRandomValues) is 'function' else random_bytes_insecure
+random_bytes = random_bytes_secure if jstype(crypto) is not 'undefined' and jstype(crypto.getRandomValues) is 'function' else random_bytes_insecure
 if random_bytes is random_bytes_insecure:
     try:
         noderandom = require('crypto').randomBytes
@@ -293,7 +292,7 @@ class ModeOfOperation:  # {{{
             return tag
         if not tag:
             return Uint8Array(0)
-        if type(tag) is 'string':
+        if jstype(tag) is 'string':
             return string_to_bytes(tag)
         raise TypeError('Invalid tag, must be a string or a Uint8Array')
 # }}}
diff --git a/resources/rapydscript/lib/elementmaker.pyj b/resources/rapydscript/lib/elementmaker.pyj
index 65620f54f4..01f4828c8d 100644
--- a/resources/rapydscript/lib/elementmaker.pyj
+++ b/resources/rapydscript/lib/elementmaker.pyj
@@ -48,11 +48,11 @@ def _makeelement(tag, *args, **kwargs):
             ans.addEventListener(attr, val)
         elif val is True:
             ans.setAttribute(vattr, vattr)
-        elif type(val) is 'string':
+        elif jstype(val) is 'string':
             ans.setAttribute(vattr, val)
 
     for arg in args:
-        if type(arg) is 'string':
+        if jstype(arg) is 'string':
             arg = this.createTextNode(arg)
         ans.appendChild(arg)
     return ans
@@ -64,7 +64,7 @@ def maker_for_document(document):
         Object.defineProperty(E, tag, {'value':_makeelement.bind(document, tag)})
     return E
 
-if type(document) is 'undefined':
+if jstype(document) is 'undefined':
     E = maker_for_document({
         'createTextNode': def(value): return value;,
         'createElement': def(name):
diff --git a/resources/rapydscript/lib/encodings.pyj b/resources/rapydscript/lib/encodings.pyj
index 3880a1338d..cd8da7041a 100644
--- a/resources/rapydscript/lib/encodings.pyj
+++ b/resources/rapydscript/lib/encodings.pyj
@@ -21,7 +21,7 @@ def base64encode(bytes):
 
 def base64decode(string):
     # convert the output of base64encode back into an array of bytes (Uint8Array)
-    if type(window) is not 'undefined':
+    if jstype(window) is not 'undefined':
         chars = window.atob(string)
     else:
         chars = new Buffer(string, 'base64').toString('binary')  # noqa: undef
@@ -106,7 +106,7 @@ def utf8_encode_js(string):
             ans.push(ch.charCodeAt(0))
     return Uint8Array(ans)
 
-if type(TextEncoder) is 'function':
+if jstype(TextEncoder) is 'function':
     _u8enc = TextEncoder('utf-8')
     utf8_encode = _u8enc.encode.bind(_u8enc)
     _u8enc = undefined
diff --git a/resources/rapydscript/lib/random.pyj b/resources/rapydscript/lib/random.pyj
index d66c8523d4..3bad097155 100644
--- a/resources/rapydscript/lib/random.pyj
+++ b/resources/rapydscript/lib/random.pyj
@@ -30,10 +30,10 @@
             ρσ_seed_state.key[ρσ_seed_state.key_j]) % 256]
 
 def seed(x=Date().getTime()):
-    if type(x) is 'number':
+    if jstype(x) is 'number':
         x = x.toString()
-    elif type(x) is not 'string':
-        raise TypeError("unhashable type: '" + type(x) + "'")
+    elif jstype(x) is not 'string':
+        raise TypeError("unhashable type: '" + jstype(x) + "'")
     for i in range(256):
         ρσ_seed_state.key[i] = i
     j = 0
diff --git a/resources/rapydscript/lib/re.pyj b/resources/rapydscript/lib/re.pyj
index 193cc94284..181ce06101 100644
--- a/resources/rapydscript/lib/re.pyj
+++ b/resources/rapydscript/lib/re.pyj
@@ -74,7 +74,7 @@ def _expand(groups, repl, group_name_map):
             return String.fromCharCode(_ASCII_CONTROL_CHARS[q])
         if '0' <= q <= '9':
             ans = read_digits(Number.MAX_VALUE, _NUM_PAT, 10, Number.MAX_VALUE, q)
-            if type(ans) is 'number':
+            if jstype(ans) is 'number':
                 return groups[ans] or ''
             return '\\' + ans
         if q is 'g':
@@ -89,17 +89,17 @@ def _expand(groups, repl, group_name_map):
                 return groups[gn] or ''
         if q is 'x':
             code = read_digits(2, _HEX_PAT, 16, 0x10FFFF)
-            if type(code) is 'number':
+            if jstype(code) is 'number':
                 return String.fromCharCode(code)
             return '\\x' + code
         if q is 'u':
             code = read_digits(4, _HEX_PAT, 16, 0x10FFFF)
-            if type(code) is 'number':
+            if jstype(code) is 'number':
                 return String.fromCharCode(code)
             return '\\u' + code
         if q is 'U':
             code = read_digits(8, _HEX_PAT, 16, 0x10FFFF)
-            if type(code) is 'number':
+            if jstype(code) is 'number':
                 if code <= 0xFFFF:
                     return String.fromCharCode(code)
                 code -= 0x10000
@@ -265,7 +265,7 @@ class MatchObject:
         return ans
 
     def _group_number(self, g):
-        if type(g) is 'number':
+        if jstype(g) is 'number':
             return g
         if has_prop(self.re.group_name_map, g):
             return self.re.group_name_map[g][-1]
@@ -273,7 +273,7 @@ class MatchObject:
 
     def _group_val(self, q, defval):
         val = undefined
-        if type(q) is 'number' and -1 < q < self._groups.length:
+        if jstype(q) is 'number' and -1 < q < self._groups.length:
             val = self._groups[q]
         else:
             if has_prop(self.re.group_name_map, q):
@@ -400,7 +400,7 @@ class RegexObject:
 
     def subn(self, repl, string, count=0):
         expand = _expand
-        if type(repl) is 'function':
+        if jstype(repl) is 'function':
             expand = def(m, repl, gnm): return '' + repl(MatchObject(self, m, 0, None))
         this._pattern.lastIndex = 0
         num = 0
diff --git a/src/pyj/book_list/prefs.pyj b/src/pyj/book_list/prefs.pyj
index 33f0333afb..dc8c7f4cd5 100644
--- a/src/pyj/book_list/prefs.pyj
+++ b/src/pyj/book_list/prefs.pyj
@@ -223,7 +223,7 @@ class PrefsPanel:
                 cls = Choices
             elif val is True or val is False:
                 cls = CheckBox
-            elif type(val) is 'number':
+            elif jstype(val) is 'number':
                 cls = SpinBox
             else:
                 cls = LineEdit
diff --git a/src/pyj/date.pyj b/src/pyj/date.pyj
index 059647b434..2c267c215c 100644
--- a/src/pyj/date.pyj
+++ b/src/pyj/date.pyj
@@ -106,7 +106,7 @@ def test_fd(date, fmt, ans):
 def format_date(date=None, fmt='dd MMM yyyy', as_utc=False):
     fmt = fmt or 'dd MMM yyyy'
     ampm = 'ap' in fmt.toLowerCase()
-    if type(date) is 'string':
+    if jstype(date) is 'string':
         date = Date(date)
     date = date or Date()
     if is_date_undefined(date):
diff --git a/src/pyj/dom.pyj b/src/pyj/dom.pyj
index be926a2ca4..68dc471c01 100644
--- a/src/pyj/dom.pyj
+++ b/src/pyj/dom.pyj
@@ -25,7 +25,7 @@ simple_vendor_prefixes = {
 }
 
 def set_css(elem, **kw):
-    if type(elem) is 'string':
+    if jstype(elem) is 'string':
         elem = document.querySelector(elem)
     s = elem.style
     if s:
diff --git a/src/pyj/popups.pyj b/src/pyj/popups.pyj
index 1f78f13cf3..1fb62a0673 100644
--- a/src/pyj/popups.pyj
+++ b/src/pyj/popups.pyj
@@ -95,7 +95,7 @@ class CompletionPopup:
         self.applied_query = ''
 
     def add_associated_widget(self, widget_or_id):
-        if type(widget_or_id) is not 'string':
+        if jstype(widget_or_id) is not 'string':
             widget_or_id = ensure_id(widget_or_id)
         self.associated_widget_ids.add(widget_or_id)
 
diff --git a/src/pyj/read_book/cfi.pyj b/src/pyj/read_book/cfi.pyj
index ff2331e1e5..08a678f69c 100644
--- a/src/pyj/read_book/cfi.pyj
+++ b/src/pyj/read_book/cfi.pyj
@@ -134,7 +134,7 @@ def encode(doc, node, offset, tail):  # {{{
 
     # Handle the offset, if any
     if node.nodeType is Node.ELEMENT_NODE:
-        if type(offset) is 'number':
+        if jstype(offset) is 'number':
             node = node.childNodes.item(offset)
     elif Node.TEXT_NODE <= node.nodeType <= Node.ENTITY_NODE:
         offset = offset or 0
@@ -388,7 +388,7 @@ def point(cfi, doc):  # {{{
     y = None
     range_ = None
 
-    if type(r.offset) is "number":
+    if jstype(r.offset) is "number":
         # Character offset
         range_ = ndoc.createRange()
         if r.forward:
@@ -435,7 +435,7 @@ def scroll_to(cfi, callback, doc):  # {{{
     if not point_:
         print("No point found for cfi: " + cfi)
         return
-    if type(point_.time) is 'number':
+    if jstype(point_.time) is 'number':
         set_current_time(point_.node, point_.time)
 
     if point_.range is not None:
@@ -486,9 +486,9 @@ def scroll_to(cfi, callback, doc):  # {{{
         fn = def():
             r = node.getBoundingClientRect()
             x, y = viewport_to_document(r.left, r.top, node.ownerDocument)
-            if type(point_.x) is 'number' and node.offsetWidth:
+            if jstype(point_.x) is 'number' and node.offsetWidth:
                 x += (point_.x*node.offsetWidth)/100
-            if type(point_.y) is 'number' and node.offsetHeight:
+            if jstype(point_.y) is 'number' and node.offsetHeight:
                 y += (point_.y*node.offsetHeight)/100
             window.scrollTo(x, y)
             if callback:
@@ -526,9 +526,9 @@ def at_point(ox, oy):  # {{{
             node = p.node
             r = node.getBoundingClientRect()
             x, y = viewport_to_document(r.left, r.top, node.ownerDocument)
-            if type(p.x) is 'number' and node.offsetWidth:
+            if jstype(p.x) is 'number' and node.offsetWidth:
                 x += (p.x*node.offsetWidth)/100
-            if type(p.y) is 'number' and node.offsetHeight:
+            if jstype(p.y) is 'number' and node.offsetHeight:
                 y += (p.y*node.offsetHeight)/100
 
         if dist(viewport_to_document(ox, oy), v'[x, y]') > 50:
diff --git a/src/pyj/read_book/mathjax.pyj b/src/pyj/read_book/mathjax.pyj
index b5726bf504..9923e4d3f6 100644
--- a/src/pyj/read_book/mathjax.pyj
+++ b/src/pyj/read_book/mathjax.pyj
@@ -8,7 +8,7 @@ def get_url(mathjax_files, name):
     ans = mathjax_files[name]
     if not ans:
         return name
-    if type(ans) is not 'string':
+    if jstype(ans) is not 'string':
         ans = mathjax_files[name] = window.URL.createObjectURL(ans)
     return ans
 
diff --git a/src/pyj/read_book/overlay.pyj b/src/pyj/read_book/overlay.pyj
index da4419f395..c88cec3acd 100644
--- a/src/pyj/read_book/overlay.pyj
+++ b/src/pyj/read_book/overlay.pyj
@@ -282,7 +282,7 @@ class Overlay:
         return document.getElementById('book-overlay')
 
     def container_clicked(self, evt):
-        if self.panels.length and type(self.panels[-1].on_container_click) is 'function':
+        if self.panels.length and jstype(self.panels[-1].on_container_click) is 'function':
             self.panels[-1].on_container_click(evt)
         else:
             self.hide_current_panel()
diff --git a/src/pyj/read_book/paged_mode.pyj b/src/pyj/read_book/paged_mode.pyj
index 34fb7f154b..e69b43e629 100644
--- a/src/pyj/read_book/paged_mode.pyj
+++ b/src/pyj/read_book/paged_mode.pyj
@@ -224,7 +224,7 @@ def scroll_to_column(number, animated=False, notify=False, duration=1000):
 def scroll_to_xpos(xpos, animated=False, notify=False, duration=1000):
     # Scroll so that the column containing xpos is the left most column in
     # the viewport
-    if type(xpos) is not 'number':
+    if jstype(xpos) is not 'number':
         print(xpos, 'is not a number, cannot scroll to it!')
         return
     if is_full_screen_layout:
diff --git a/src/pyj/read_book/resources.pyj b/src/pyj/read_book/resources.pyj
index 8743ed9af3..64e4d350f3 100644
--- a/src/pyj/read_book/resources.pyj
+++ b/src/pyj/read_book/resources.pyj
@@ -34,7 +34,7 @@ def load_resources(db, book, root_name, previous_resources, proceed):
             return setTimeout(do_one, 0)
         if previous_resources[name]:
             ans[name] = data = previous_resources[name]
-            if type(data[0]) is 'string':
+            if jstype(data[0]) is 'string':
                 find_virtualized_resources(data[0])
             return setTimeout(do_one, 0)
         db.get_file(book, name, got_one)
@@ -44,7 +44,7 @@ def load_resources(db, book, root_name, previous_resources, proceed):
             # Enable to have cover image not preserve aspect ratio
             data = data.replace('width: auto', 'width: 100%')
         ans[name] = v'[data, mimetype]'
-        if type(data) is 'string':
+        if jstype(data) is 'string':
             find_virtualized_resources(data)
         return setTimeout(do_one, 0)
 
@@ -88,7 +88,7 @@ def finalize_resources(book, root_name, resource_data):
     # Resolve the non virtualized resources immediately
     for name in resource_data:
         data, mimetype = resource_data[name]
-        if type(data) is not 'string':
+        if jstype(data) is not 'string':
             blob_url_map[name] = window.URL.createObjectURL(data)
     for name in blob_url_map:
         v'delete resource_data[name]'
diff --git a/src/pyj/read_book/ui.pyj b/src/pyj/read_book/ui.pyj
index 05b9b18dd2..a2d66d672b 100644
--- a/src/pyj/read_book/ui.pyj
+++ b/src/pyj/read_book/ui.pyj
@@ -136,7 +136,7 @@ class ReadUI:
         self.current_metadata = metadata or {'title':_('Book id #') + book_id}
         get_boss().update_window_title()
         self.init_ui()
-        if type(self.db) is 'string':
+        if jstype(self.db) is 'string':
             self.show_error(_('Cannot read book'), self.db)
             return
         self.db.get_book(book_id, fmt, metadata, self.got_book.bind(self, force_reload))
diff --git a/src/pyj/read_book/view.pyj b/src/pyj/read_book/view.pyj
index 083d194535..eae7d74766 100644
--- a/src/pyj/read_book/view.pyj
+++ b/src/pyj/read_book/view.pyj
@@ -242,7 +242,7 @@ class View:
                 snum = int(snum)
             except Exception:
                 print('Invalid spine number in CFI:', snum)
-            if type(snum) == 'number':
+            if jstype(snum) == 'number':
                 name = book.manifest.spine[(int(snum) // 2) - 1] or name
                 pos.type, pos.cfi = 'cfi', '/' + rest
         self.show_name(name, initial_position=pos)
diff --git a/src/pyj/session.pyj b/src/pyj/session.pyj
index bd0704ce4a..a0c9a300e5 100644
--- a/src/pyj/session.pyj
+++ b/src/pyj/session.pyj
@@ -66,7 +66,7 @@ class FakeStorage:
         return self.data[key]
 
     def setItem(self, key, value):
-        if type(value) is not 'string':
+        if jstype(value) is not 'string':
             value = JSON.stringify(value)
         self.data[key] = value