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)."

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."

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."

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.