How to delete html comments in php

In PHP, you can use the preg_replace() function with regular expressions to delete html comments. This function can perform a regular expression search and replacement; the specific syntax format is "preg_replace('##','',string)".

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

How to delete html comments in php

The first thing that is more basic is:

    $a = &#39;<!--ceshi-->ceshi&#39;;
    $a = preg_replace(&#39;#<!--.*-->#&#39; , &#39;&#39; , $a);
    var_dump($a);

The above code will output ceshi.

But if it is the following string, it cannot achieve the effect we want

    $a = &#39;<!--ceshi-->ceshi<!--ceshi-->&#39;;
    $a = preg_replace(&#39;#<!--.*-->#&#39; , &#39;&#39; , $a);
    var_dump($a);

So we changed the matching rules to the following format

preg_replace(&#39;#<!--.*?-->#&#39; , &#39;&#39; , $a);

But in If there is code like <!--[if lt IE 9]>ceshi<![endif]--> in html, it cannot be removed, so we need to improve the matching rules and change Into the following format

preg_replace(&#39;#<!--[^\!\[]*?-->#&#39; , &#39;&#39; , $a);

and then if there is <script><!--ceshi//--></script> code in the html, we need Let’s change our matching rules to the following format

preg_replace(&#39;#<!--[^\!\[]*?(?<!\/\/)-->#&#39; , &#39;&#39; , $a);

In this case, I will basically remove the html comments that I need to remove!

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