Hello, I am here to report an improvement for your dev team.

Problem:
Cannot include '<=' in textarea field. The content after '<=' will be discarded or will malfunction. 

Scenario (used case):
When you want to show some arithmetic comparison, ex: a <= 100. 

Analyze:  
In wpdatatables/controllers/wdt_ajax_actions.php, there is code (my class is modified and can't refer correct lines) that will strip '<='. To overcome this, make sure before the code is stripped, try to change it to some other tag name that will not be stripped, ex: "myUniqueID". Add this line before sanitize data:

//change "<=" to "myUniqueID"
$formData[$column->orig_header] = preg_replace("/<=/", "myUniqueID", $formData[$column->orig_header]);

Once all the sanitization are complete, remember to change 'myUniqueID' back to '<='.

//change "myUniqueID" back to "<="
$formData[$column->orig_header] = preg_replace("/myUniqueID/", "<=", $formData[$column->orig_header]);

Do the same thing for the excel one as well if needed.

Hi Aleksandar,

No problem. Actually, I thought hard about it. It is not a bug technically speaking, it is the nature of how stripping tag is and how the DOM tree is processed. I understand the concern of possible client side attack but that is actually the fault on the client side for allowing inputting malicious code.

My use case here is to put some code snippet using textarea field. The '<=' is one of the things that discards my whole written content. There is another scenario in which I want to type '<<'  to indicate left shift operator (programming wise) and since the DOM cannot interpret the text correctly, hence the content after '<<' is discarded. As the result, I commented the lines that strip tags and process DOM. 

Hope this provides some insights for your dev team.