Following is the code to validate any textbox or input text against html tags.
//source and args are required if calling from custom validator in asp.net else its not required function htmlValidation(source,args) { var re = /(<([^>]+)>)/gi; if (document.getElementById(’<%=TextBox2.ClientID%>’).value.match(re)) { document.getElementById(’<%=TextBox2.ClientID%>’).value = “”; alert(’Invalid content’); //args.IsValid = false; // you can use this if you are calling this from custom validator in asp.net return false; } if (document.getElementById("textboxid").value.match(re)) { document.getElementById("textboxid").value = “”; alert(’Invalid content’); return false; } return true; }