用户复制和粘贴内容时，如何根据禁止的输入检查复制的数据？

Question

I am developing one application that has form builder inside it to build the form. In that, i have considered special character '#' & '[]' for backend data processing against form & so i have banned user from typing the key buttons on keyboard for the respective characters too. Thing is i am done with banning user from typing so but if user copies the content from somewhere & paste into the place which supposed to contain above characters the i want to check before user pastes, the data against banned inputs. My concern is this but dont know how to do it or is it possible to do so or any other way to resolve this issue???

Thanks in advance for inputs...

Answer 1

Preventing the user from pressing unwanted keyes is not the best way to solve this problem. In principle you have two problem domains:

1) Preventing malicious inputs from your form to go over the wire. The best way to do that would be to use jQuery submit() and write a validation function which a) cleans input and sends it over the wire or b) prevents submitting and shows the user an error message, not to enter malicious input.

2) You have to be concerned, that the user could bypass your form implementation and uses curl or other tools to circumvent validation on site. So, you have to take care in the backend, that the input is sanitized, before processed further.

Answer 2

 $("textarea").bind('paste', function(e) {
      var self = this;
      setTimeout(function(e) {
           var textval=$(self.val());
           //Replace the banned keys with your custom
           $("textarea").val(textval);
      }, 0);
 });

Answer 3

Try something like this:

 $('#yourTextAreaId').on('paste', function (e) { 
        pasteContent = e.target.value;

        //implement containsSpecialChars function
        if(containsSpecialChars(pasteContent)){ 
           e.preventDefault()
        }
    });