script.js

$(document).ready(function() {
  var $keys = $('.calculator button');
  var $screen = $('.screen');
  var decimal = false;
  var operators = ['+', '-', 'x', '÷'];

  $keys.click(function() {
    var keyVal = $(this).data('val');
    output = $('.screen').html();

    console.log(keyVal);

    // clear
    if (keyVal == 'clear') {
      $screen.html('');
      decimal = false;
    }
    // equal
    else if (keyVal == '=') {
      var equation = output;
      var lastChar = equation[equation.length - 1];
      equation = equation.replace(/x/g, '*').replace(/÷/g, '/');
      if (operators.indexOf(lastChar) > -1 || lastChar == '.')
        equation = equation.replace(/.$/, '');
      if (equation) {
        $screen.html(eval(equation));
      }
      decimal = false;
    }
    // operators
    else if ($(this).parent().is('.operators')) {
      var lastChar = output[output.length - 1];
      if (output != '' && operators.indexOf(lastChar) == -1) {
        $screen.html($screen.html() + keyVal);
      } else if (output == '' && keyVal == '-') {
        $screen.html($screen.html() + keyVal);
      }
      if (operators.indexOf(lastChar) > -1 && output.length > 1) {
        $screen.html($screen.html().replace(/.$/, keyVal));
      }
      decimal = false;
    }
    // decimal
    else if (keyVal == '.') {
      if (!decimal) {
        $screen.html($screen.html() + keyVal);
        decimal = true;
      }
    }
    // buttons
    else {
      $screen.html($screen.html() + keyVal);
    }
  });

  $(window).keydown(function(e) {
    console.log(e.which);
    switch (e.which) {
      case 96:
        key = 0;
        break;
      case 97:
        key = 1;
        break;
      case 98:
        key = 2;
        break;
      case 99:
        key = 3;
        break;
      case 100:
        key = 4;
        break;
      case 101:
        key = 5;
        break;
      case 102:
        key = 6;
        break;
      case 103:
        key = 7;
        break;
      case 104:
        key = 8;
        break;
      case 105:
        key = 9;
        break;
      case 111:
        key = '÷';
        break;
      case 109:
        key = '-';
        break;
      case 106:
        key = 'x';
        break;
      case 107:
        key = '+';
        break;
      case 13:
        key = '=';
        break;
      case 110:
        key = '.';
        break;
      case 27:
        key = 'clear';
        break;
      default:
        return false;
    }

    $('[data-val="' + key + '"]').addClass('active').click();
  }).keyup(function() {
    $('.active').removeClass('active');
  });


  $('[data-val="clear"]').click().delay(100).queue(function() {
    $('[data-val="1"]').click().delay(200).queue(function() {
      $('[data-val="5"]').click().delay(200).queue(function() {
        $('[data-val="x"]').click().delay(200).queue(function() {
          $('[data-val="3"]').click();
        });
      });
    });
  });
});