qtjavascript.qdoc

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// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
/*!
  \page qtjavascript.html
  \title Making Applications Scriptable
  \ingroup frameworks-technologies
  \brief incorporating JavaScript in Qt applications.
 
  Qt provides support for application scripting with JavaScript.
  The following guides and references cover aspects of programming with
  JavaScript and Qt.
 
  \tableofcontents
 
  \section1 Scripting Classes
 
  The following classes add scripting capabilities to Qt applications.
 
  \annotatedlist qtjavascript
 
  \section1 Basic Usage
 
  To evaluate script code, you create a QJSEngine and call its
  evaluate() function, passing the script code (text) to evaluate
  as argument.
 
  \snippet qtjavascript/evaluation/main.cpp 0
 
  The return value will be the result of the evaluation (represented
  as a QJSValue object); this can be converted to standard C++
  and Qt types.
 
  Custom properties can be made available to scripts by registering
  them with the script engine. This is most easily done by setting
  properties of the script engine's \e{Global Object}:
 
  \snippet qtjavascript/registeringvalues/main.cpp 0
 
  This places the properties in the script environment, thus making them
  available to script code.
 
  \section1 Making a QObject Available to the Script Engine
 
  Any QObject-based instance can be made available for use with scripts.
 
  When a QObject is passed to the QJSEngine::newQObject() function,
  a Qt Script wrapper object is created that can be used to make the
  QObject's signals, slots, properties, and child objects available
  to scripts.
 
  Here's an example of making an instance of a QObject subclass
  available to script code under the name \c{"myObject"}:
 
  \snippet qtjavascript/registeringobjects/main.cpp 0
 
  This will create a global variable called \c{myObject} in the
  script environment. The variable serves as a proxy to the
  underlying C++ object. Note that the name of the script variable
  can be anything; i.e., it is not dependent upon QObject::objectName().
 
  \section1 Implications for Application Security
 
  The security model of application scripting with JavaScript follows
  the same model as for C++ code: the user installs scripts to run
  that they trust in the same way as they install Qt applications.
 
  In order to preserve the trust of users, application developers should
  not evaluate arbitrary JavaScript code. The JavaScript engine's sandbox is
  only a semantic barrier. The script is evaluated in the same process and
  with the same privileges as the rest of the application and shares the
  same memory. As a consequence, C++ objects exposed to scripts are
  accessible without additional security guards.
 */