JSFiddle - React, Tailwind, and code Playground

JavaScript

function addMinutesToTime(time, minsAdd) {
  function z(n){ return (n<10? '0':'') + n;};
  var bits = time.split(':');
  var mins = bits[0]*60 + +bits[1] + +minsAdd;
  return z(mins%(24*60)/60 | 0) + ':' + z(mins%60);  
} 
result=addMinutesToTime('5:31',30);
alert(result);