JSFiddle - React, Tailwind, and code Playground

JavaScript

var val1 = 65.00;
var val2 = 47.09;

if(val1%1==0){val1--;month1=12;};
var year1 = Math.floor(val1);
if(month1!=12)
var month1 = ((val1%1)/12)*100;
else month1=1;

if(val2%1==0){val2--;month2=12;};
var year2 = Math.floor(val2);
if(month2!=12)
var month2 = ((val2%1)/12)*100;
else month2 = 1;


var YearResult = Math.abs((year1-year2));
var monthResult = Math.round(Math.abs((month1 - month2))*12);

var result = YearResult+'.'+monthResult;
console.log(result);