isRutLike()

Quick format check to determine if a string looks like a RUT, without validating the verifier digit.

Basic Usage


import { isRutLike } from 'rut.ts'
 
isRutLike('12.345.678-9')  // true
isRutLike('not-a-rut')     // false

Type Signature


function isRutLike(rut: string): boolean

Parameters

rut (string) - The string to check

Return Value

Returns boolean:

true if the string looks like a RUT format
false otherwise

Examples

Valid Formats


import { isRutLike } from 'rut.ts'
 
// All RUT-like formats
isRutLike('12.345.678-9')   // true (standard format)
isRutLike('12345678-9')     // true (no dots)
isRutLike('123456789')      // true (no formatting)
isRutLike('1.234.567-K')    // true (7-digit body)
isRutLike('09.068.826-K')   // true (leading zeros)

Invalid Formats


import { isRutLike } from 'rut.ts'
 
isRutLike('abcdefgh')      // false (letters)
isRutLike('')              // false (empty)
isRutLike('12.34.56-7')    // false (wrong dot pattern)
isRutLike('12,345,678-9')  // false (commas not supported)

Difference from validate()

isRutLike() only checks if the format looks correct. It does NOT validate the verifier digit.

Use validate() for full validation including verifier digit check.


import { isRutLike, validate } from 'rut.ts'
 
const rut = '12.345.678-0' // Wrong verifier (should be 5)
 
isRutLike(rut)   // true ✅ (format is correct)
validate(rut)    // false ❌ (verifier is wrong)

Use Cases

Early Form Validation


import { isRutLike } from 'rut.ts'
 
function handleInput(value: string) {
  if (!isRutLike(value)) {
    showError('Please enter a valid RUT format')
    return
  }
  
  // Continue with full validation
  if (validate(value)) {
    saveRut(value)
  }
}

Filter Lists


import { isRutLike } from 'rut.ts'
 
const inputs = [
  '12.345.678-5',
  'invalid',
  '18.972.631-7',
  'abc',
  '9068826K'
]
 
// Quick filter for RUT-like strings
const potentialRuts = inputs.filter(isRutLike)
console.log(potentialRuts)
// ['12.345.678-5', '18.972.631-7', '9068826K']

Pre-validation Check


import { isRutLike, validate } from 'rut.ts'
 
function validateRut(input: unknown): boolean {
  // Quick type/format check first
  if (typeof input !== 'string' || !isRutLike(input)) {
    return false
  }
  
  // Then do full validation (more expensive)
  return validate(input)
}

Performance

isRutLike() is faster than validate() because:

Only checks format with regex
Doesn’t calculate verifier digit
Doesn’t decompose the RUT

Use it for quick filtering before full validation.

validate() - Full validation with verifier check
format() - Format RUT strings
clean() - Clean RUT strings