use-validated-state

Manages state with validation

Import

Usage

use-validated-state validates state with a given rule each time state is set. It returns an object with current validation state, last valid value and current value:

const [{ lastValidValue, value, valid }, setValue] = useValidatedState(
  'valid',
  (value) => value === 'valid'
);

lastValidValue; // -> valid
value; // -> valid
valid; // -> true

setValue('invalid');

lastValidValue; // -> valid
value; // -> invalid
valid; // -> false

Example

Current value: [empty string]

Last valid value: [empty string]

import { TextInput, Text, Box } from '@mantine/core';
import { useValidatedState } from '@mantine/hooks';

function Demo() {
  const [{ value, lastValidValue, valid }, setEmail] = useValidatedState(
    '',
    (val) => /^\S+@\S+$/.test(val),
    true
  );

  return (
    <Box maw={320} mx="auto" style={{ overflowWrap: 'break-word' }}>
      <TextInput
        value={value}
        onChange={(event) => setEmail(event.currentTarget.value)}
        withAsterisk
        error={!valid}
        placeholder="email@example.com"
        label="Your email"
      />

      <Text size="sm" mt="md">
        <Text inherit c="dimmed" component="span">
          Current value:
        </Text>{' '}
        {value || '[empty string]'}
      </Text>

      <Text size="sm">
        <Text inherit c="dimmed" component="span">
          Last valid value:
        </Text>{' '}
        {lastValidValue || '[empty string]'}
      </Text>
    </Box>
  );
}

Definition

function useValidatedState<T>(
  initialValue: T,
  validation: (value: T) => boolean,
  initialValidationState?: boolean
): [
  {
    value: T;
    lastValidValue: T;
    valid: boolean;
  },
  (val: T) => void
];