Rules List

Built-in Rules

The following validation rules are included with js-validation:

required

Validates that the field has a non-empty value (after trimming whitespace).

rules: {
  name: { required: true }
}

Default message: "This field is required."

email

Validates that the value is a properly formatted email address.

rules: {
  email: { required: true, email: true }
}

Default message: "Please enter a valid email address."

url

Validates that the value is a properly formatted URL.

rules: {
  url: { required: true, url: true }
}

Default message: "Please enter a valid URL."

date

Validates that the value can be parsed as a valid date.

rules: {
  birthday: { date: true }
}

Default message: "Please enter a valid date."

dateISO

Validates that the value matches ISO-like date format (YYYY-MM-DD or YYYY/MM/DD).

rules: {
  startDate: { dateISO: true }
}

Default message: "Please enter a valid ISO date (YYYY-MM-DD)."

time

Validates time in H:MM, HH:MM, or HH:MM:SS format.

Available since v1.4.0.

rules: {
  startTime: { time: true }
}

Default message: "Please enter a valid time (HH:MM or HH:MM:SS)."

minlength

Validates that the value has at least the specified number of characters.

rules: {
  password: { minlength: 6 }
}

Default message: "Please enter at least {0} characters."

maxlength

Validates that the value has no more than the specified number of characters.

rules: {
  username: { maxlength: 20 }
}

Default message: "Please enter no more than {0} characters."

range

Validates that the numeric value is between a minimum and maximum (inclusive).

rules: {
  age: { range: [18, 65] }
}

Default message: "Please enter a value between {0} and {1}."

Invalid format message: "Please enter a valid range."

Wrong format cases — the rule returns false and the invalid format message is shown when:

• range is a single number (e.g. range: 5)
• range is an array with fewer than two elements (e.g. range: [2])
• range is an unparseable string (e.g. range: 'invalid')
• range is null or any other non-array value

pattern

Validates that the value matches a regular expression pattern.

rules: {
  zipcode: { pattern: '^[0-9]{5}$' }
}

Default message: "Please match the requested format."

equalTo

Validates that the value matches the value of another field (useful for password confirmation).

rules: {
  confirmPassword: { equalTo: '#password' }
}

Default message: "Please enter the same value again."

notEqualTo

Validates that the value is different from the value of another field. Useful for requiring a new value, such as a new password that must differ from the current password.

Available since v1.3.0.

rules: {
  newPassword: { notEqualTo: '#currentPassword' }
}

Default message: "Please enter a different value."

numeric

Validates that the value contains only numeric digits (0-9).

rules: {
  age: { numeric: true }
}

Default message: "Please enter only numeric values."

ipv4

Validates that the value is a properly formatted IPv4 address.

rules: {
  serverIp: { ipv4: true }
}

Default message: "Please enter a valid IPv4 address."

ipv6

Validates that the value is a properly formatted IPv6 address. Supports full, compressed, and mixed IPv4-in-IPv6 notations.

rules: {
  serverIp: { ipv6: true }
}

Default message: "Please enter a valid IPv6 address."

alphanumeric

Validates that the value contains only letters (a–z, A–Z), digits (0–9), and underscores. Spaces and special characters are not allowed.

rules: {
  username: { alphanumeric: true }
}

Default message: "Please enter only letters, numbers, and underscores."

alpha

Validates that the value contains only alphabetic letters (a–z, A–Z). Digits, spaces, underscores, and special characters are not allowed.

Available since v1.4.0.

rules: {
  firstName: { alpha: true }
}

Default message: "Please enter only alphabetic letters."

ishexcolor

Validates that the value is a valid CSS hex color. Accepts both 3-digit (e.g. #fff) and 6-digit (e.g. #ffffff) formats, case-insensitively.

rules: {
  brandColor: { ishexcolor: true }
}

Default message: "Please enter a valid hex color (e.g. #fff or #ffffff)."

maxfiles

Validates that a file input does not contain more than the specified number of selected files. Pair it with the multiple attribute when users can upload more than one file.

Available since v1.3.0.

rules: {
  attachments: { maxfiles: 3 }
}

Default message: "Please select no more than {0} files."

maxsize

Validates that every selected file is within the specified size limit. The parameter can be a number of bytes or a string using B, KB, MB, or GB.

Available since v1.3.0.

rules: {
  attachments: { maxsize: '2MB' }
}

Default message: "Please select files no larger than {0}."

maxsizetotal

Validates that all selected file is within the specified size limit. The parameter can be a number of bytes or a string using B, KB, MB, or GB.

Available since v1.3.0.

rules: {
  attachments: { maxsizetotal: '2MB' }
}

Default message: "Total size of all files must not exceed {0}."

Using Rules via HTML Attributes

All rules can also be declared using data-rule-* attributes:

<input name="email" data-rule-required="true" data-rule-email="true" />
<input name="password" data-rule-required="true" data-rule-minlength="6" />
<input name="zipcode" data-rule-pattern="^[0-9]{5}$" />

Custom Error Messages via HTML

Use data-msg-* attributes to override default messages:

<input
  name="email"
  data-rule-required="true"
  data-msg-required="Email is required!"
/>

Combining Rules

Multiple rules can be applied to a single field. They are evaluated in order:

rules: {
  username: {
    required: true,
    minlength: 3,
    maxlength: 20,
    pattern: '^[a-zA-Z0-9_]+$'
  }
}

Rule Evaluation

• Rules are evaluated in the order they are defined.
• Validation stops at the first failing rule for each field.
• A rule with a value of false or "false" is skipped.

See Also

• Custom Rules – How to create your own validation rules.