check whether any html tags entered in textarea using javascript

Question

I'm having a simple commenting system, where i want the user should not type any html special chars, if they done like that they should give an alert of "html tags not allowed". How to do it?

while submitting, a ajax call is passed to another page to store it in db.

So in the javascript itself(before ajax call), how to find is there any html tags in the entered comment.

Any suggestion.

The question refers to “html entities”, then “html tags”. They are two different things. The question should be edited to make it unambiguous which one is meant (or whether you mean both tags and entities). — Jukka K. Korpela
– Jukka K. Korpela, Commented Mar 1, 2015 at 13:42

KooiInc · Accepted Answer · 2015-03-01 09:19:47Z

2

To check you can create an element in the DOM, inject the comment into it and use [element].getElementsByTagName('*') to check for any html element. If its length is not 0, there are html elements in the comment. Something like:

document.querySelector('#check').addEventListener('click', doCheck);

function doCheck(e) {
 var chkEl = document.createElement('div'), 
     isok,
     report,
     value = document.querySelector('#testing').value;
 if (!value.length) {return true;}
 chkEl.innerHTML = value;
 report = document.querySelector('[data-report]');
 isok = !chkEl.getElementsByTagName('*').length;
 report.setAttribute( 'data-report',
                 !isok 
                 ? 'you can\'t enter html here!' 
                 : 'text looks ok' );
 report.style.color = isok ? 'green' : 'red';
}

[data-report]:before {
  content: attr(data-report);
}

<textarea id="testing" placeholder="type some stuff"></textarea>
<span data-report=""></span>
<br>
<button id="check">check for html</button>

Disclaimer: you should always check server side too.

edited Mar 1, 2015 at 9:19

answered Mar 1, 2015 at 9:02

KooiInc

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1 Comment

user3784251 Over a year ago

Thank you. Here element denotes what??

Community · Accepted Answer · 2017-05-23 11:56:55Z

1

You can use the following statement with regex:

if (/<[a-z][\s\S]*>/i.test(textareaContent)) {
  alert("html tags not allowed");
}

Kooilnc is right. You should always check user input on server side as well.

Please see this question Check if a string is html or not

edited May 23, 2017 at 11:56

CommunityBot

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answered Mar 1, 2015 at 9:04

Timur Osadchiy

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Comments

LeulAria · Accepted Answer · 2022-06-15 07:58:30Z

0

removing html tags in comment

function sanitizeString(str) {
    str = str.replace(/[^a-z0-9áéíóúñü \.,_-]/gim, " ");    
    return str.trim();
}

answered Jun 15, 2022 at 7:58

LeulAria

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