Starts With

Validates that a value starts with a given prefix string.

Configuration

Config flag	Type	Description
`startsWith`	`string`	The required prefix.
`startsWith`	`[string, string]`	Tuple form — the prefix plus a custom message.

const form = useForm({
  initialValues: { orderId: '' },
  validationSchema: {
    orderId: { startsWith: 'ORD-' },
  },
});

With a custom message:

orderId: { startsWith: ['ORD-', 'Order IDs start with ORD-'] }

import { V } from 'formify-js';

V.startsWith('ORD-');

Scenario	Message
Value does not start with the prefix	`Must start with "ORD-"` (the message names your prefix)

Value	Rule	Result
`'ORD-123'`	`startsWith: 'ORD-'`	✅ Valid
`'123-ORD'`	`startsWith: 'ORD-'`	❌ Invalid

The check is case-sensitive: 'ord-123' fails when the prefix is 'ORD-'.
Combine with pattern or other rules when the remainder of the value also has a format.