How do I check if textarea is HTML?

Question

How do I check if what was written in the textarea by the user is valid HTML? It could be with either PHP or Javascript.

Maybe you can use http://www.php.net/manual/en/domdocument.loadhtml.php - after load you can loaded with input using `similar_text` — Ragen Dazs, Feb 19 '14 at 03:24

Cilan · Answer 1 · 2014-02-19T22:22:19.760

0

In php, it would be quite simple:

if($text!=htmlspecialchars($text))
{
    echo 'This contains HTML tags!!';
}

Of course, this means an ampersand would be valid, so you could also do something like

function hasHtml($string) {
    if ( $string != strip_tags($string) )
        return true;
}

You can use John Resig's html parser for the Javascript solution, or do something like this:

function is_html(string)
{
  return string.match("/<[^<]+>/").length != 0;
}

edited Feb 19 '14 at 22:22

answered Feb 19 '14 at 03:24

Cilan

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2

Checking via htmlspecialchars would mean any string with an ampersand in it would return valid? – flauntster Feb 19 '14 at 03:28
2

That's not going to tell the OP that the contents are *valid* HTML (regardless of what the OP means by valid) – Mark Parnell Feb 19 '14 at 03:29

score 0 · Answer 2 · answered Feb 19 '14 at 03:27

0

You could post the contents to a html validation script or online service and show the result.

You may also want to investigate the PHP DOMDocument class which has some validating functionality.

answered Feb 19 '14 at 03:27

flauntster

2,008
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score 0 · Answer 3 · answered Feb 19 '14 at 03:40

in js, it's easy since it has an HTML parser built-in:

function isHTML(str){
  var div=document.createElement("div");
  div.innerHTML=str;
  return div.children.length>0;
}

note that this will validate that there is some well-formed html, or html that quirks into well-formed html. strict validity is another matter, and only FireFox lets you ajax view-source: urls to sniff for error title attribs in the gecko html display markup. Other browsers will need a server-side proxy to the w3 validator, or a on-site html validation service provided by your own server.

How do I check if textarea is HTML?

3 Answers3