Validation.js

$.validator.addMethod("pan", function (value, element) {
    return this.optional(element) || /^[A-Z]{5}\d{4}[A-Z]{1}$/.test(value);
}, "Please enter a valid PAN");

$.validator.addMethod("gst", function (value, element) {
    return this.optional(element) || /^([0]{1}[1-9]{1}|[1-2]{1}[0-9]{1}|[3]{1}[0-7]{1})([a-zA-Z]{5}[0-9]{4}[a-zA-Z]{1}[1-9a-zA-Z]{1}[zZ]{1}[0-9a-zA-Z]{1})+$/.test(value);
}, "Please enter a valid GST No");

$.validator.addMethod('filesize', function (value, element, param) {
  if (element.files.length) {
      return this.optional(element) || (element.files[0].size <= param)
  }
  return true;
}, 'File size must be less than 5mb.');

$.validator.addMethod("unique", function(value, element, params) {
    var prefix = params;
    var selector = jQuery.validator.format("[name!='{0}']{1}", element.name, prefix);
    var matches = new Array();
    $(selector).each(function(index, item) {
        if (value == $(item).val()) {
            matches.push(item);
        }
    });
    return matches.length == 0;
}, "Value is not unique.");

$.validator.addMethod('lessThanEqual', function (value, element, param) {
    return this.optional(element) || parseInt(value) <= parseInt($(param).val());
},function (params, element) {
    console.log(params, element);
    return "The value " + $(element).val() + " must be less than or equal " + $(params).val();
});