pattern

The string matches a regular expression.

Signature

function pattern(re: RegExp, msg?: Message): Action<string>

Parameters

Parameter	Type	Description
re	RegExp	Regular expression
msg	Message	Custom error message. A string with {params} or a function

Error codes

Code	When	Default message
pattern	The string does not match	Invalid format

You can change the texts: see Messages & i18n.

Notes

• Use ^ and $: without them /\d+/ accepts 'abc1', because it finds a digit inside the string.
• The g flag is safe — lastIndex is reset before each check.

Examples

Phone

pipe(string(), pattern(/^\+1\d{10}$/, 'Format: +1XXXXXXXXXX'))

Slug

pipe(string(), pattern(/^[a-z0-9]+(-[a-z0-9]+)*$/))

See also

• email
• length
• check — when a regex is not enough