使用正则表达式在字符串中查找不匹配字符

Question

I have to find and show to user any special character other than keyboard characters in text area when text entering/pasting the text, here below I explained what am try to do! Please help me as soon as possible?

if ($(txtMessage).val().trim() != "") {
         var pattern = "^[a-zA-Z0-9~`!@#$%^&*()_+-={}|:;<>,.?\/']+$";
         for(var i=0;i<$(txtMessage).val().length;i++){
             var subStr=$(txtMessage).val().substring(0, i);
             if(!subStr.match(pattern)){
                 $('#customDailogBox')
                    .text(
                            "You have entered or paste "+subStr.substring(i, i)+"input  characters are not supported characters!!!..");
             }
         }

Answer 1

change your loop condition and the substring function

 for(var i=1;i=<$(txtMessage).val().length;i++){
         var subStr=$(txtMessage).val().substr(i,1);
         if(!subStr.match(pattern)){
             $('#customDailogBox').text("You have entered or paste "+subStr.substring(i, i)+"input  characters are not supported characters!!!..");
         }
}

or you can also use the regular expression to match the whole string once

var unmatched_characters = $(txtMessage).val().match(/[^a-zA-Z0-9~`!@#$%^&*()_+-={}|:;<>,.?\/']/g);
if (unmatched_characters.length>0){
     $('#customDailogBox').text("You have entered or paste some characters that are not supported !!!..");
}