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Validating a form in javascript

By finding ways of injecting malicious scripts into web pages, an attacker can gain elevated access-privileges to sensitive page content, to session cookies, and to a variety of other information maintained by the browser on behalf of the user.

Cross-site scripting attacks are a case of code injection.

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For example, suppose there is a dating website where members scan the profiles of other members to see if they look interesting.Although widely recommended, performing HTML entity encoding only on the five XML significant characters is not always sufficient to prevent many forms of XSS attacks.As encoding is often difficult, security encoding libraries are usually easier to use.) will not suffice since the user input needs to be rendered as HTML by the browser (so it shows as "very large", instead of "very large").A classic example of a potential vector is a site search engine: if one searches for a string, the search string will typically be redisplayed verbatim on the result page to indicate what was searched for.If this response does not properly escape or reject HTML control characters, a cross-site scripting flaw will ensue.Some sources further divide these two groups into traditional (caused by server-side code flaws) and DOM-based (in client-side code).These holes show up when the data provided by a web client, most commonly in HTTP query parameters (e.g.If the trusted site is vulnerable to the vector, clicking the link can cause the victim's browser to execute the injected script.The persistent (or stored) XSS vulnerability is a more devastating variant of a cross-site scripting flaw: it occurs when the data provided by the attacker is saved by the server, and then permanently displayed on "normal" pages returned to other users in the course of regular browsing, without proper HTML escaping.Exploiting one of these, attackers fold malicious content into the content being delivered from the compromised site.When the resulting combined content arrives at the client-side web browser, it has all been delivered from the trusted source, and thus operates under the permissions granted to that system.


  1. Cross-site scripting XSS is a type of computer security vulnerability typically found in web applications. XSS enables attackers to inject client-side scripts into.

  2. Click here for comprehensive JavaScript tutorials, and over 400+ free scripts!

  3. JavaScript Form Validation. HTML form validation can be done by JavaScript. If a form field fname is empty, this function alerts a message.

  4. MyObject"property" With dot notation, the property name is hard-coded and cannot be changed at run-time. With bracket notation, the property name is a string which.

  5. Validating User Input. In Web Pages 2, you can use the Validator helper to test user input. The basic approach is to do the following Determine which input.

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