JSFiddle - React, Tailwind, and code Playground

JavaScript

var main=function(operand1,operand2,operator) {
  var concat,number;
  var operand1=romantonumerals(operand1);
  var operand2=romantonumerals(operand2);
  //var operator=operatorconversion(operator);
  console.log("operand1 "+operand1);
  console.log("operand2 "+operand2);
  if(operand1>operand2) {
    concat=operand1+operator+operand2;
  }
  else {
    concat=operand2+operator+operand1;
  }
  number=Math.round(eval(concat));
  console.log(number);
  if(number<500) {
    result=numeralstoroman(number)
  }
  else if(number===0) {
    result="Make sure its greater than 0";
  }
  else {
    result="Make sure your number gets less than 500 try with some other romans";
  }
  console.log(result);
  return result;
};
var numeralstoroman=function(number) {
  var roman="",temp;
  var ones=function(number) {
    switch (number) {
      case 1:
        roman+="I";
        break;
      case 2:
        roman+="II";
        break;
      case 3:
        roman+="III";
        break;
      case 4:
        roman+="IV";
        break;
      case 5:
        roman+="V";
        break;
      case 6:
        roman+="VI";
        break;
      case 7:
        roman+="VII";
        break;
      case 8:
        roman+="VIII";
        break;
      case 9:
        roman+="IX";
        break;
    }
  };
  var twos=function(number) {
    if(number>=10 && number<20) {
      roman+="X";
      ones(number%10);
    }
    else if(number>=20 && number30) {
      roman+="XX";
      ones(number%10);
    }
    else if(number>=30 && number<40) {
      roman+="XXX";
      ones(number%10);
    }
    else if(number>=40 && number<50) {
      roman+="XL";
      ones(number%10);
    }
    else if(number>=50 && number<60) {
      roman+="L";
      ones(number%10);
    }
    else if(number>=60 && number<70) {
      roman+="LX";
      ones(number%10);
    }
    else if(number>=70 && number<80) {
      roman+="LXX";
      ones(number%10);
    }
    else if(number>=80 && number<90) {
      roman+="LXXX";
     ...