textbox should not allow html data using regular expression

Question

<input type="text" id="NotesReturn" />
<script type="text/javascript">
    $("#NotesReturn").keypress(function (e) {
         kCode = e.keyCode || e.charCode
         var htmlRegExp=new RegExp("/<(\w+)((?:\s+\w+(?:\s*=\s*(??:'[^']*')|(?:'[^']*')|[^>\s]+))?)*)\s*(\/?)>/");
         if (htmlRegExp.test(kCode) || $(this).val().length >= 512)
            e.preventDefault();
    });

    $("#NotesReturn").bind('paste', function(e){
         var pastedValue=this.value+window.clipboardData.getData('Text');
         var trimmedValue=pastedValue.substring(0, 512);
         var htmlRegExp = new RegExp("/<(\w+)((?:\s+\w+(?:\s*=\s*(??:'[^']*')|(?:'[^']*')|[^>\s]+))?)*)\s*(\/?)>/");
         if(!htmlRegExp.test(trimmedValue))
         {
             $(this).val(null);
             $(this).val(trimmedValue.toString());
         }
         e.preventDefault();
    });

</script>

My textbox should not allow html data.But it is throwing unexpected quantifier error.can someone help me.I could not figure out the error.

The parentheses in your regexp aren't balanced. And you shouldn't put / at the beginning and end when you use new RegExp(), you only do that when writing the regex as a literal. — Barmar
– Barmar, Commented Jan 8, 2013 at 3:18
I don't get "unexpected quantifier". Chrome complains "Invalid group". — Barmar
– Barmar, Commented Jan 8, 2013 at 3:19

MikeM · Accepted Answer · 2013-01-09 12:41:26Z

1

The unexpected quantifier error is due to the ?? in (??: which should probably be simply (?: to indicate a non-capturing group.
As Barmer stated, the opening and closing forward slashes should not be included and the round brackets are unbalanced. You need to remove a right round bracket or add another left one.
You also need to escape the backslashes by preceding them with a backslash when using the RegExp constructor.
Doing the above will give you a valid regex but whether it will work correctly to disallow html is another question.

edited Jan 9, 2013 at 12:41

answered Jan 8, 2013 at 15:57

MikeM

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