How do I get a JavaScript interpreter

Deactivate JavaScript: Instructions for Firefox, Chrome and IE

In principle, JavaScript is a Computer language with very limited permissions. The scripting language essentially allows ...

  • manipulate the current browser window via DOM (Document Object Model),
  • open new browser or dialog windows,
  • To animate, show and hide page elements or to change their design,
  • Validate input values,
  • Reload ajax,
  • Transfer information about the user's reading habits and browsing activities to other websites.

JavaScript only receives access to the Internet user's cookies and other data storage devices reserved for websites. A website operator cannot access the browser user's hard drive via JavaScript. With the script language, libraries can neither be called nor follow-up programs started on the computer. This is ensured by the so-called Sandbox principle, which limits the scope of influence of scripts to the respective browser window in which JavaScript is executed.

Nonetheless, JavaScript still offers a certain amount of leeway for manipulation. An improper use of JavaScript enables, for example:

  • Read information about the browser or the operating system of an Internet user in order to record their Internet behavior or to identify security gaps (e.g. outdated plug-ins),
  • Open countless pop-up windows to paralyze the Internet user's computer (Denial of Service, DoS for short),
  • disguise malicious code
  • Simulate websites of trustworthy providers in the context of phishing attacks.

In addition, program errors sometimes only come into play when a script is running on the user's computer.

The central security risk, however, is less the scripting language than the respective one JavaScript interpreter in the browser. If this is incorrect, a security gap arises that must be closed immediately. This is the only way to ensure that scripts run in isolation in the sandbox and cannot influence other programs or the underlying system.