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POBest way for form validation in PHP and JS
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copied!<p>I was wondering what actually the best way for a solid form validation is.</p> <p>JavaScript does a quite good jon, but it is not a base for a solid validation, because it can be manipulated or even disabled.</p> <p>If you check the data with PHP and re-populate a form when an error occurrs, there are several problems with a post form. </p> <ul> <li>If the form is displayed without redirecting, then F5 will show a confirm box if the user wants to re-send the data, this is not really beautiful.</li> <li>If the user gets redirected to the form again, the data must be submitted by <code>GET</code> or <code>POST</code>. With <code>POST</code>, there is again the F5-Problem as mentioned above. With <code>GET</code>, a problem exists when transferring values with a <code>&</code> inside (PHP guesses another parameter after the sign)</li> <li>A third way would be to store the data in a database, e.g. SUBMITTRIALS or something like that. But then you'd actually have to clear the data after redirecting.</li> </ul> <p>Another problem comes along with re-populating of the form itself: A code like this:</p> <pre><code>echo "<input type='text' value='".$val."' />"; </code></pre> <p>is quite a problem if the variable <code>$val</code> contains a value containing apostrophes, this generates invalid HTML.</p> <p>As you can see, there are quite much possibilities of failure in a form validation scenario. What would be the most reliable way to handle form-validation as described at top?</p>

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