nhducit/Regex maskify.md

## Regex maskify.md

      
    Raw
  

              Regex maskify.md
            
          
    Question:
write a function maskify, which changes all but the last four characters into '#'
Eg:
maskify('4556364607935616') # should return '############5616'
maskify('64607935616')      # should return '#######5616'
maskify('1')                # should return '1'
maskify('')                 # should return ''

Answer:
function maskify(input){
  return input.replace(/.(?=....)/g, '#')
}