Filter dangerous html code in form submission using php

Html code that uses PHP to filter submitted forms may contain code that introduces external dangerous content. For example, when a user submits a form that contains html content, the layout of the displayed page may be messy, the html code that needs to be filtered out using PHP to filter the submitted form may be exploited to introduce external dangerous content. For example, some forms submitted by the user contain html content, but this may cause confusion in the layout of the display page and need to be filtered out.
The following is the program code:

Function uhtml ($ str) { $ Farr = array ( "// \ S +/", // filter unnecessary spaces // Filter scripts and other code that may introduce malicious content or maliciously change the display layout. if you do not need to insert flash, you can also addFilter "/<(\/?) (Script | I? Frame | style | html | body | title | link | meta | \? | \ %) ([^>] *?)> /IsU ", "/(<[^>] *) On [a-zA-Z] + \ s * = ([^>] *>)/isU ", // filter javascript on events ); $ Tarr = array ( "", "<\ 1 \ 2 \ 3>", // If you want to directly clear insecure labels, leave it blank. "\ 1 \ 2 ", ); $ Str = preg_replace ($ farr, $ tarr, $ str ); Return $ str; }