script.js

function getHistory() {
  return document.getElementById("history-value").innerText;
}
function printHistory(num) {
  document.getElementById("history-value").innerText = num;
}
function getOutput() {
  return document.getElementById("output-value").innerText;
}
function printOutput(num) {
  if (num == "") {
    document.getElementById("output-value").innerText = num;
  } else {
    document.getElementById("output-value").innerText = getFormattedNumber(num);
  }
}
function getFormattedNumber(num) {
  if (num == "-") {
    return "";
  }
  var n = Number(num);
  var value = n.toLocaleString("en");
  return value;
}
function reverseNumberFormat(num) {
  return Number(num.replace(/,/g, ""));
}
var operator = document.getElementsByClassName("operator");
for (var i = 0; i < operator.length; i++) {
  operator[i].addEventListener("click", function () {
    if (this.id == "clear") {
      printHistory("");
      printOutput("");
    } else if (this.id == "backspace") {
      var output = reverseNumberFormat(getOutput()).toString();
      if (output) {
        output = output.substr(0, output.length - 1);
        printOutput(output);
      }
    } else {
      var output = getOutput();
      var history = getHistory();
      if (output == "" && history != "") {
        if (isNaN(history[history.length - 1])) {
          history = history.substr(0, history.length - 1);
        }
      }
      if (output != "" || history !== "") {
        output = output == "" ? output : reverseNumberFormat(output);
        history = history + output;
        if (this.id == "=") {
          var result = eval(history);
          printOutput(result);
          printHistory("");
        } else {
          history = history + this.id;
          printHistory(history);
          printOutput("");
        }
      }
    }
  });
}

var number = document.getElementsByClassName("number");
for (var i = 0; i < number.length; i++) {
  number[i].addEventListener("click", function () {
    var output = reverseNumberFormat(getOutput());
    if (output != NaN) {
      output = output + this.id;
      printOutput(output);
    }
  });
}
var microphone = document.getElementById("microphone");
microphone.onclick = function () {
  microphone.classList.add("record");
  var recognition = new (window.SpeechRecognition ||
    webkitSpeechRecognition ||
    windows.mozSpeechRecognition ||
    window.msSpeechRecognition)();
  recognition.lang = "en-US";
  recognition.start();
  operations = {
    plus: "+",
    minus: "-",
    "substracted by": "-",
    into: "*",
    "multiplied by": "*",
    divide: "/",
    "divided by": "/",
    reminder: "%",
  };
  recognition.onresult = function (event) {
    var input = event.results[0][0].transcript;
    for (property in operations) {
      input = input.replace(property, operations[property]);
    }
    document.getElementById("output-value").innerText = input;
    setTimeout(function () {
      evaluate(input);
    }, 2000);
    microphone.classList.remove("record");
  };
};
function evaluate(input) {
  try {
    var result = eval(input);
    document.getElementById("output-value").innerText = result;
  } catch (e) {
    console.log(e);
    document.getElementById("output-value").innerText = "";
  }
}