Question

I’d like to know the possible Regex suitable for checking a string that includes certain HTML tags, namely, <b>, <i> and <a> or it has no any tags. using PHP preg_match.

For example:

"This a text only.." return true
"This is a <b>bold</b> text" return true
"this is <script>alert('hi')</script>" return false
"this is <a href="#">some</a>and <h1>header</h1>" return false

Answer 1

Try using strip_tags() instead. Regular expressions aren’t suited for parsing HTML tags.

var_dump(isTextClean('This a text only..')); // true
var_dump(isTextClean('This is a <b>bold</b> text')); // true
var_dump(isTextClean('this is <script>alert(\'hi\')</script>')); // false
var_dump(isTextClean('this is <a href="#">some</a>and <h1>header</h1>')); // false

function isTextClean($input) {
    $result = strip_tags($input, '<b><i><a>');

    if ($result != $input) {
        return false;
    } else {
        return true;
    }
}