diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -175,6 +175,10 @@
    core/synctex/synctex_parser_utils.c
 )
 
+qt5_add_resources(okularcore_SRCS
+   core/script/builtin.qrc
+)
+
 ki18n_wrap_ui(okularcore_SRCS
    conf/textdocumentsettings.ui
 )
diff --git a/core/script/builtin.js b/core/script/builtin.js
new file mode 100644
--- /dev/null
+++ b/core/script/builtin.js
@@ -0,0 +1,62 @@
+/***************************************************************************
+ *   Copyright (C) 2018        Intevation GmbH <intevation@intevation.de>  *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ ***************************************************************************/
+
+/* Builtin functions for Okular's PDF JavaScript interpretation. */
+
+/** AFSimple_Calculate
+ *
+ * cFunction is a string that identifies the operation.
+ *           It is one of AVG, SUM, PRD, MIN, MAX
+ * cFields is an array of the names of the fields used to calculate.
+ */
+function AFSimple_Calculate( cFunction, cFields )
+{
+    var ret = 0;
+
+    if ( cFunction === "PRD" )
+    {
+        ret = 1;
+    }
+
+    for (i = 0; i < cFields.length; i++)
+    {
+        var field = Doc.getField( cFields[i] );
+        var val = Number( field.value );
+
+        if ( cFunction === "SUM" || cFunction === "AVG" )
+        {
+            ret += val;
+        }
+        else if ( cFunction === "PRD" )
+        {
+            ret *= val;
+        }
+        else if ( cFunction === "MIN" )
+        {
+            if ( i === 0 || val < ret )
+            {
+                ret = val;
+            }
+        }
+        else if ( cFunction === "MAX" )
+        {
+            if ( i === 0 || val > ret )
+            {
+                ret = val;
+            }
+        }
+    }
+
+    if ( cFunction === "AVG" )
+    {
+        ret /= cFields.length;
+    }
+
+    event.value = ret;
+}
diff --git a/core/script/builtin.qrc b/core/script/builtin.qrc
new file mode 100644
--- /dev/null
+++ b/core/script/builtin.qrc
@@ -0,0 +1,5 @@
+<!DOCTYPE RCC><RCC version="1.0">
+<qresource prefix="/script">
+    <file>builtin.js</file>
+</qresource>
+</RCC>
diff --git a/core/scripter.cpp b/core/scripter.cpp
--- a/core/scripter.cpp
+++ b/core/scripter.cpp
@@ -10,6 +10,7 @@
 #include "scripter.h"
 
 #include <QtCore/QDebug>
+#include <QFile>
 
 #include "debug_p.h"
 #include "script/executor_kjs_p.h"
@@ -53,14 +54,29 @@
     else
         qDebug() << script.left( 1000 ) << "[...]";
 #endif
+    static QString builtInScript;
+    if ( builtInScript.isNull() )
+    {
+        QFile builtInResource ( ":/script/builtin.js" );
+        if (!builtInResource.open( QIODevice::ReadOnly ))
+        {
+            qCDebug(OkularCoreDebug) << "failed to load builtin script";
+        }
+        else
+        {
+            builtInScript = QString::fromUtf8( builtInResource.readAll() );
+            builtInResource.close();
+        }
+    }
+
     switch ( type )
     {
         case JavaScript:
             if ( !d->m_kjs )
             {
                 d->m_kjs = new ExecutorKJS( d->m_doc );
             }
-            d->m_kjs->execute( script, d->m_event );
+            d->m_kjs->execute( builtInScript + script, d->m_event );
             break;
     }
     return QString();