CheerpJ converts Java apps into JavaScript for the web

Convertation of applications and Java libraries  to web applications is no longer challenge. CheerpJ has managed to develop an unique technology
26 June 2017   1974

Java is a popular general-purpose programming language and computing platform

CheerpJ is the Java compiler for Web applications which serves to convert any Java application and library to a browser-based Web application effortlessly.

The CheerpJ Applet Viewer extension, created by Leaning Technologies and based on the CheerpJ technology, takes Java bytecode and turns it into JavaScript without needing the Java source or any plugin. Converted applications that can be deployed on a web server via both jar.js JavaScript and .jar files.


JavaScript is a lightweight interpreted or JIT-compiled programming language with first-class functions

Bidirectional liaison between Java and JavaScript is quite challenging for any JavaScript library and browser API from Java as well.

The most important features of Cheerp®J are following:

  • open-source compiler based on LLVM
  • native JavaScript memory model
  • clean access to HTML5 DOM
  • optimized performances and output size
  • JavaScript  interoperability

CheerpJ can generate Java archive (.jar) files as well as one single files including both reflection and dynamic classes.

The Applet Viewer extension compiles the Java applet on the fly, without relying on any remote server. The extension will be available on different popular browsers such as GWT(Google Web Toolkit) and Chrome that are running in a beta release now.

Compared with other technologies, Learning Technologies has no partial implementation of the Java runtime library, they rather convert than adapt to new applications. Technologies, which compile to JavaScript from other languages, include Scala.js, the Kotlin language, and Microsoft’s TypeScript.

Using The CheerpJ Applet Viewer requires no effort and installation of the extension proceeds just one click, creating the icon in the upper right corner of Chrome.
A restricted public release of CheerpJ is expected to be released in the upcoming July. As for a commercial version, it will roll out in the autumn.

New Vulnerability to be Found in Google+

Due to this vulnerability it was possible to obtain private information of 52.5 million accounts
11 December 2018   105

Google decided to close the social network Google+ not in August 2019, but in April. The reason was another vulnerability in the API, due to which it was possible to obtain private information of 52.5 million accounts. The company plans to close the social network API until mid-March 2019.

By December 10, 2018, the following error information was published:

  • Third-party applications requesting access to profile data, because of the bug in the API, received permission to view information, even if it is hidden by privacy settings;
  • the names of users, their email addresses, information about occupation, age and other confidential information were at risk;
  • passwords, financial data and national identification numbers have not been compromised;
  • the company has no evidence that anyone has exploited the vulnerability;
  • the error was fixed within 6 days: from November 7 to November 13, 2018.
  • Google said it sends notifications to all users affected by the bug.

The previous data leak of Google+ users occurred in October 2018. Then about 500 thousand accounts were compromised. The attackers could get the names, email addresses, age, gender and occupation of users.