Starts With modifier

A modifier which creates a validation rule to ensure that a given string starts with a specific prefix.

Schemas

string: Learn more

Arguments

prefix - The prefix that the string must start with
message? - A custom object with error messages to be displayed when validation fails or there are type errors

Example

import { startsWith, string } from '@nordic-ui/validathor';
 
const startsWithRule = string([
  startsWith('https://', {
    prefix_error: "Must start with https://",
  }),
]);
 
try {
  const parsedValue = startsWithRule.parse('https://example.com');
  console.log('Parsed value:', parsedValue);
} catch (error) {
  console.error('Parsing failed:', error.message);
}

Validation Details

The startsWith modifier:

Performs case-sensitive prefix matching
Can check for any string prefix, not just single characters
Returns the original string if validation passes

Common Use Cases

import { startsWith, string, url } from '@nordic-ui/validathor';
 
// Ensure secure URLs
const secureUrlRule = string([
  startsWith('https://'),
  url(),
]);
 
// Validate file paths
const absolutePathRule = string([
  startsWith('/', {
    prefix_error: "Must be an absolute path",
  }),
]);
 
// Check for specific prefixes
const phoneWithCountryRule = string([
  startsWith('+', {
    prefix_error: "Must include country code",
  }),
]);
 
// Validate namespaced keys
const configKeyRule = string([
  startsWith('app.config.', {
    prefix_error: "Must be a config key",
  }),
]);

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