JSFiddle - React, Tailwind, and code Playground

by Rajesh Dixit

JavaScript

var A = ['6-2', '7+3', '8*1', '9/3', '8+1'];
var B = ['1+5', '7-3', '10-5', '10/2', '3*2'];

var len = Math.max(A.length, B.length);

for(var i=0; i<len; i++){
	var r1 = evaluate(A[i]);
  var r2 = evaluate(B[i]);
  
	var msg = "It's "+ (+r1 > +r2 ? "Bigger": "Smaller");
  console.log(msg, r1, r2);
}

function evaluate(str) {
  var opReg = /[-+\/\*]/g;
  var op_arr = str.match(opReg);
  var result = 0;
  var sortOrder = {
    "*": 1,
    "/": 2,
    "+": 3,
    "-": 4
  }
  op_arr.sort(function(a,b) {
  	var s1 = sortOrder[a];
    var s2 = sortOrder[b];
    return s1>s2 ? 1 : s1<s2 ? -1 : 0;
  }).forEach(function(op) {
    var val_arr = getValueArr(str, op)
    result = calculate(val_arr, op);
    str = str.replace(val_arr[0] + op + val_arr[1], result)
  });
  return result;
}

function getValueArr(str, op) {
  var r = str.split(op);
  var v1 = 0;
  var v2 = 0;
  var opReg = /[-+\/\*]/g;
  v1 = opReg.test(r[0]) ? r[0].split(opReg).reverse()[0] : r[0];
  v2 = opReg.test(r[1]) ? r[1].split(opReg)[0] : r[1];
  return [v1, v2];
}

function calculate(val, op) {
  switch (op) {
    case "-":
      return +val[0] - +val[1];
    case "+":
      return +val[0] + +val[1];
    case "*":
      return +val[0] * +val[1];
    case "/":
      return +val[0] / +val[1];
  }
  return 0;
}
evaluate('6-2+4*2')