[JavaScript]
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Limitations

What are JavaScript's limitations? There are quite few (it's a scripting language, after all, not a full-fledged programming language). The most significant is that JavaScript works entirely within the browser on the client (user's) system, and can access only those objects which the browser currently stores in the computer's dynamic memory. Specifically:

  • JavaScript cannot write information to any file on the user's computer (except to a cookie file) or the server, so no information generated by the script or the user's interaction with it is saved, unless you work with cookies
  • By the same token, JavaScript cannot create any files or pages (JavaScript can "write" HTML pages in a sense, but only to the extent that it can choose and combine various pieces of pre-defined code made available to it)
  • JavaScript cannot manipulate any peripheral devices
  • JavaScript cannot manipulate or access any program aside from the browser

Note that these limitations can also be seen as safety devices -- neither you nor the user who looks at your web pages need fear that your JavaScript will damage his or her software, data, or computer in any way. The worst your script can do is produce an error message if it doesn't run properly.

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