<!--<div id="errorbox"><ul></ul></div>-->
 
$(document).ready(function(){
    $("#commentForm").validate({
 
    errorContainer: "#errorbox",
    errorLabelContainer: "#errorbox ul",
    wrapper: "li",
    rules: {
    	name: "required",
    	email: {
    		required: true,
    		email: true,
    	},
    	comment: "required"
    },
	messages: {
    	comment: "This is a comment form. Why in the heck would you leave the comment blank?",
    	email: {
    		required: "Email address is required.",
    		email: "Email addresses are of the form user@host. Not yourRstupid."
    	},
    	name: {
    		required: "Stand up for your comments or go home."
    	}
    }
 
    });
});
//
$(document).ready(function(){
    $("#commentForm").validate({
 
    rules: {
    	name: {
    		required: true,
    		minlength: 2
    	},
    	email: {
    		required: "#csub:checked",
    		email: true,
    	},
    	comment: "required"
    },
    messages: {
    	comment: "This is a comment form. Why in the heck would you leave the comment blank?",
    	email: {
    		required: "Dude, you want the newsletter, but you didn't enter an email address?",
    		email: "Email addresses are of the form user@host. Not yourRstupid."
    	},
    	name: {
    		required: "Stand up for your comments or go home.",
    		minlength: jQuery.format("You need to use at least {0} characters for your name.")
    	}
    }
 
    });
});
//
$(document).ready(function(){
 
	$.validator.addMethod("noanon", function(value) {
			return value.toLowerCase().indexOf("anonymous") != 0;
		}, 'Do not hide behind the cover of anonymity');
 
    $("#commentForm").validate({
 
    rules: {
    	name: {
    		required: true,
    		minlength: 2,
    		noanon: true
    	},
    	email: {
    		required: "#csub:checked",
    		email: true,
    	},
    	comment: "required"
    },
    messages: {
    	comment: "This is a comment form. Why in the heck would you leave the comment blank?",
    	email: {
    		required: "Dude, you want the newsletter, but you didn't enter an email address?",
    		email: "Email addresses are of the form user@host. Not yourRstupid."
    	},
    	name: {
    		required: "Stand up for your comments or go home.",
    		minlength: jQuery.format("You need to use at least {0} characters for your name.")
    	}
    }
 
    });
});
 
//
<tr>
  <td>Phone</td>
  <td><input name="phone" type="text" id="phone" class="required NumbersOnly"></td>
</tr>
 
<script>
  $(document).ready(function(){
    $.validator.addMethod("NumbersOnly", function(value, element) {
        return this.optional(element) || /^[0-9\-\+]+$/i.test(value);
    }, "Phone must contain only numbers, + and -.");
 
    $("#regForm").validate();
  });
  </script>
 
<script>
  $(document).ready(function(){
    $.validator.addMethod("username", function(value, element) {
        return this.optional(element) || /^[a-z0-9\_]+$/i.test(value);
    }, "Username must contain only letters, numbers, or underscore.");
 
    $("#regForm").validate();
  });
  </script>
 
Finally, i somehow got hold of the code that does the job through regular expression regex that checks for only numbers and a-z
1
2
3
4
5
6
7
8
9
10
 
<script>
$(document).ready(function(){
 
    $.validator.addMethod("noSpecialChars", function(value, element) {
      return this.optional(element) || /^[a-z0-9\_]+$/i.test(value);
  }, "Username must contain only letters, numbers, or underscore.");
 
  $("#myForm").validate();
});
</script>