JSFiddle - React, Tailwind, and code Playground
JavaScript
var replacement = {
'Б': 'больше',
'М': 'меньше'
};
function replacer(match, p1){
return replacement[p1];
};
var string = '4 5п -М 5, 5 1п -Б 4\r\n2 0п -Б 1';
console.log(string.replace(/[0-9]п \-(М|Б)/g, replacer));