This article was originally published at [https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589](https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589).
### Presence[](https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589#presence) - **exists -** The field must exist, and not be `undefined`. - **required -** The field must exist, and not be `undefined`, `null` or an empty string. - **empty -** The field must be some kind of "empty". Things that are considered "empty" are as follows: - `""` (empty string) - `[]` (empty array) - `{}` (empty object) - Other falsey values ### Character set[](https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589#character-set) - **alpha -** `a-z`, `A-Z` - **alphaNumeric -** `a-z`, `A-Z`, `0-9` - **alphaUnderscore -** `a-z`, `A-Z`, `0-9`, `_` - **alphaDash -** `a-z`, `A-Z`, `0-9`, `_`, `-` ### Value[](https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589#value) Length-related validators may apply to both strings and arrays. - **exactLength:`length`-** The value must have a length of exactly `length`. - **minLength:`length` -** The value must have a length of at least `length`. - **maxLength:`length` -** The value must have a length of at most `length`. - **contains:`needle` -** The value must contain the specified `needle` (applies to both strings and arrays). - **accepted -** Must be a value that indicates agreement - varies by language (defaulting to `en`): - **en, fr, nl -** `"yes"`, `"on"`, `"1"`, `1`, `"true"`, `true` - **es -** `"yes"`, `"on"`, `"1"`, `1`, `"true"`, `true`, `"si"` - **ru -** `"yes"`, `"on"`, `"1"`, `1`, `"true"`, `true`, `"да"` ### Value (numbers)[](https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589#value-numbers) Note that "numbers" refers to both Number-type values, and strings containing numeric values! - **numeric -** Must be a finite numeric value of some sort. - **integer -** Must be an integer value (either positive or negative). - **natural -** Must be a natural number (ie. an integer value of 0 or higher). - **naturalNonZero -** Must be a natural number, but *higher* than 0 (ie. an integer value of 1 or higher). - **between:`min`:`max` -** The value must numerically be between the `min` and `max` values (exclusive). - **range:`min`:`max` -** The value must numerically be *within* the `min` and `max` values (inclusive). - **lessThan:`maxValue` -** The value must numerically be less than the specified `maxValue` (exclusive). - **lessThanEqualTo:`maxValue` -** The value must numerically be less than *or equal to* the specified `maxValue` (inclusive). - **greaterThan:`minValue` -** The value must numerically be greater than the specified `minValue` (exclusive). - **greaterThanEqualTo:`minValue` -** The value must numerically be greater than *or equal to* the specified `minValue` (inclusive). ### Relations to other fields[](https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589#relations-to-other-fields) - **matchesField:`field` -** The value in this field must equal the value in the specified other `field`. - **different:`field` -** The value in this field must *not* equal the value in the specified other `field`. ### JavaScript types[](https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589#javascript-types) - **NaN -** Must be `NaN`. - **null -** Must be `null` - **string -** Must be a `String`. - **number -** Must be a `Number`. - **array -** Must be an `Array`. - **plainObject -** Must be a plain `object` (ie. object literal). - **date -** Must be a `Date` object. - **function -** Must be a `Function`. - **regExp -** Must be a `RegExp` object. - **arguments -** Must be an `arguments` object. ### Format[](https://gist.github.com/joepie91/cd107b3a566264b28a3494689d73e589#format) - **email -** Must be a validly formatted e-mail address. - **luhn -** Must be a validly formatted creditcard number (according to a Luhn regular expression). - **url -** Must be a validly formatted URL. - **ipv4 -** Must be a validly formatted IPv4 address. - **ipv6 -** Must be a validly formatted IPv6 address. - **uuid -** Must be a validly formatted UUID. - **base64 -** Must be a validly formatted base64 string.