Example input 1: '1 JAN' Expected output: 'd MMM'
'1 JAN'
'd MMM'
Example input 2: 'JAN 31' Expected output: 'MMM dd'
'JAN 31'
'MMM dd'
You can do it yourself.
for (let str of ['1 JAN', 'JAN 31']) { console.log (str.replaceAll(/\p{L}/gu, 'M').replaceAll(/\d/g, 'd')); }