Outputting a comparison of the differences between

Question

I'm trying to create a simple nutrition calculator that outputs the difference between two foods. You put in an amount in the textbox, select 2 food options and a comparison should spit out the differences between the foods.

Code I have so far:

var stocks = [
  ["Beef (80/20) raw","oz",115.4451262,2.094125,1.199617347,72,4.85,5.65,0,2.142,19,20,0.0001275510204,0.375,0.75,22.15988372,0.3768292943,4  ],
  ["Beef (90/10) raw","oz",115.4451262,2.094125,1.199617347,50,5.65,2.83,0,1.109,19,18,0.0001275510204,0.375,0.75,22.15988372,0.3768292943,4  ],
  ["Chicken breast","oz",32.39053977,0.320375,0.07197704082,34,6.38,0.74,0,0.16,13,21,0.01631172356,0.10625,0.2125,3.149953226,0.3765300698,4  ],
  ["Chicken thighs/legs","oz",32.39053977,0.320375,0.07197704082,125,2.72,12.54,0,3.431,14,30,0.01631172356,0.10625,0.2125,3.149953226,0.3765799405,4  ],
  ["Milk (whole)","fl oz",7.638924987,0.146025,0.0002099330357,19,0.96,0.99,1.54,0.569,13,0.000000357142857142857,0.099609375,0.19921875,1.228661955,0.2415694159,8  ],
  ["Milk (2%)","fl oz",7.638924987,0.06112164455,0.0002099330357,15,1.06,0.58,1.54,0.363,16,2,0.000000357142857142857,0.099609375,0.19921875,1.228661955,0.2417190282,8  ],
  ["Pizza (cheese)","slice",42,0.9700347449,0.006297991071,285,12.19,10.37,3.83,4.778,640,18,0.00001071428571,2.98828125,5.9765625,36.85985865,0.466697922,4  ],
  ["Ice Cream","cup",32.59312,0.6168324833,0.002345956329,274.71344,4.6095984,14.4806576,27.9835216,8.94913952,107.09168,55.87392,0.000003990994286,1.11311325,2.2262265,13.73003196,2.889031735,1  ],
  ["Milk (skim)","fl oz",7.638924987,0.05927058824,0.0002099330357,10,1.03,0.02,1.54,0.017,13,1,0.000000357142857142857,0.099609375,0.19921875,1.228661955,0.2415694159,8  ],
  ["Eggs (large)","each",43.13341461,0.514206,0.007354326122,78,6.29,5.3,0.2,1.633,62,186,0.001666666667,0.265625,0.53125,3.713549,0.1305756192,1  ],
  ["Lamb","oz",78.125,2.8105,1.199617347,80,4.69,6.64,0,2.889,17,21,0.03333333333,0.3125,0.625,2.274815967,0.3767295528,4  ],
  ["Cheese (hard)","slice (oz)",37.44571072,1.35025,0.002099330357,105,6.59,8.41,0.14,5.32,159,27,0.000003571428571,0.99609375,1.9921875,12.28661955,0.1303337926,1  ],
  ["Yogurt","oz",5.833333333,0.09375,0.0002099330357,17,0.98,0.92,1.32,0.595,13,4,0.000000357142857142857,0.099609375,0.19921875,1.228661955,0.2229453548,6  ],
  ["Greek yogurt, vanilla (nonfat)","fl oz",15,0.08232711306,0.0005248325893,22,2.45,0.05,1.01,0.038,10,1,0.000000892857142857143,0.3984375,0.796875,3.071654888,0.1965527472,6  ],
  ["Chocolate","oz",127.316,0.1862906,0.00004198660714,151,2.16,8.39,14.57,5.238,22,7,0.0000000714285714285714,0.019921875,0.03984375,1.601963425,1.345070603,1.45  ],
  ["Cacao","oz",179.739,0.625,0,136,1.19,8.51,15.45,5.032,3,0,0,0,0,3.390577585,1.418619303,1.45  ],
  ["Salmon (farmed)","oz",0.498125,0.56925,0,59,5.79,3.8,0,0.864,17,16,0.004464285714,0.078125,0.15625,0.5593288054,0.3767295528,4  ],
  ["Tuna (canned in oil)","oz",0.498125,0.1197485281,0,56,8.26,2.33,0,0.435,118,5,0.000270197828,1.0625,2.125,0.5593288054,0.3817664985,4  ],
  ["Mayo","oz",14.41309121,0.121875,0.001838581531,193,0.27,21.22,0.16,3.318,180,12,0.0004166666667,0.06640625,0.1328125,0.92838725,0.1330741748,0.5  ],
  ["Pulled Pork raw","oz",44.84498316,0.63525,0.1411314526,53,4.94,3.5,0,1.232,17,18,0.0005208333333,0.21875,0.4375,1.592371177,0.3767295528,4  ],
  ["Butter (salted)","oz",41.58720633,0.5875,0.00440859375,203,0.24,22.95,0.02,14.537,182,61,0.0000075,2.091796875,4.18359375,25.80190106,0.121322241,1  ],
  ["Soy Burger","oz",21.8,0.048125,0,50,4.44,1.78,0.3,0.408,161,1,0,0,0,2.314125,0.03342563782,4  ],
  ["Vegan Nuggets (soy)","oz",21.8,0.048125,0,52,4.88,1.63,0.65,0.325,172,0,0,0,0,2.314125,0.06360340429,4  ],
  ["Soymilk (original)","fl oz",2.319532348,0.02445449777,0,17,1,0.54,1.21,0.063,16,0,0,0,0,1.168382863,0.1032302684,8  ],
  ["Tofu","oz",25.25,0.09625,0,23,2.82,1.49,0.2,0.26,1,0,0,0,0,4.62825,0.01698083545,4  ],
  ["Tempeh","oz",12.383064,0.0230998152,0,54,5.74,3.06,0,0.719,3,0,0,0,0,1.110771114,0.0001496122504,4  ],
  ["Mixed Nuts","oz",18.72285536,0.18425,0,172,5.53,15.17,1.42,2.271,1,1,0,0,0,1.019662873,0.1202597201,1  ],
  ["Bread","slice",9.735884788,0.1530147137,0,79,3.09,1.31,1.66,0.202,137,0,0,0,0,0.5625,0.1473592997,2  ],
  ["Lentils","oz",30.3684714,0.07425,0,33,2.55,0.11,0.51,0.015,1,0,0,0,0,2.287814892,0.04322383072,7.1  ],
  ["Black Beans","oz",30.3684714,0.141625,0,37,2.31,0.1,0.09,0.025,1,0,0,0,0,1.555714169,0.007668804863,7.1  ],
  ["Tomato Sauce","oz",3.13704,0.09375,0,11,0.47,0.06,1.37,0.008,57,0,0,0,0,0.4188459746,0.1188197409,8  ],
  ["Pinto Beans","oz",30.3684714,0.141625,0,40,2.55,0.18,0.09,0.038,0,0,0,0,0,0.9075003086,0.007618934113,7.1  ],
  ["French Fries","oz",2.9337142,0.0417335921,0,56,0.82,1.91,0.14,0.359,113,0,0,0,0,0.4200133922,0.01748707005,4  ],
  ["Peanut Butter","oz",36,0.2145,0,167,6.81,14.13,2.97,2.153,138,0,0,0,0,3.675378676,0.2583069893,1  ],
  ["Olive Oil","oz",21.77842536,0.2306145384,0,250,0,28.3,0,3.908,1,0,0,0,0,1.512500057,0.00004987075014,0.5  ],
  ["Banana","1 medium",6.440662244,0.1763699536,0,105,1.29,0.39,14.43,0.132,1,0,0,0,0,0.1768995697,1.221618974,1  ],
  ["Mixed vegetables","oz",2.41150377,0.125,0,18,0.81,0.04,0,0.009,10,0,0,0,0,3,0.0004987075014,4  ],
  ["Nutritional Yeast","g",0.08506329224,0.00706361088,0,3.9859577,0.5989518739,0,0,0,0,0,0,0,0,0,0,5  ],
  ["Rice (white)","oz",25.46308329,0.34375,0,102,1.87,0.16,0,0.045,0,0,0,0,0,0.3995205753,0,2  ],
  ["Potatoes","oz",1.872285536,0.03575,0,16,0.73,0.03,0.2,0.007,3,0,0,0,0,0.06927480776,0.01708057695,5.3  ],
  ["Vegetable Oil","oz",17.70433203,0.125,0,205,0,23.8,0,19.937,0,0,0,0,0,5.300817694,0,0.5  ],
  ["Wheat (flour)","1/4 cup",10.11034189,0.03087703323,0,102,3.39,0.47,0.09,0.069,1,0,0,0,0,0.3995205753,0.007668804863,1  ],
  ["Margarine","oz",9.915624199,0.06125,0,102,0.28,11.32,0,2.048,222,0,0,0,0,5.300817694,0.01107130653,1  ],
  ["Corn Syrup","fl oz",11.15931776,0.01728062914,0,109,0,0,29.31,0,1,0,0,0,0,0.4854914297,2.481282747,1  ],
  ["Sugar","oz",11.23371322,0.01503093504,0,110,0,0,28.3,0,0,0,0,0,0,0.4340729937,2.395731504,1  ],
  ["Corn (grain)","oz",6.74022793,0.0104375,0,103,2.67,1.34,0.18,0.189,10,0,0,0,0,0.4549631935,0.01573657573,1  ],
  ["Soda","fl oz",10.64647779,0.02494335117,null,13,0,0.08,3.05,0,1,0,0,0,0,0.1939638153,0.2582470824,12  ]
]

$(".selectStock").each(function (){
  for (var i = 0, len = stocks.length; i < len; i++) {
 $("<option>").html(stocks[i][0]).attr("value", i).appendTo(this);
}
});

function r2d (i) {
  return Math.round(i * 100) / 100
}

$(".selectStock").change(updateAmount);
$("#numberOfStocks").on('keyup', updateAmount);

function updateAmount() {
  $(".selectStock").each(function () {
    index = Number($(this).val());
    if (isNaN(index)) {
      return;
    }
    amt = Number($("#numberOfStocks").val());
    if (isNaN(amt) || amt == 0) {
      amt = stocks[index][17];
    }
    $(this).nextAll(".result:first").html("")
      .append((Math.round(stocks[index][2] * amt * 100)/100).toLocaleString() + " gallons of water<br />")
      .append((r2d(amt*stocks[index][3])).toLocaleString() + " mg of vitamin B12<br />")
      .append((Math.round(stocks[index][4] * amt * 100)/100).toLocaleString()+ " mg of vitamin A<br />")
      .append((r2d(amt*stocks[index][5])).toLocaleString() + " calories<br />")
      .append((Math.round(stocks[index][6] * amt * 100)/100).toLocaleString() + " g of protein<br />")
    .append((Math.round(stocks[index][7] * amt * 1000)/1000).toLocaleString() + " g of fat <br />")
    .append((Math.round(stocks[index][9] * amt * 100)/100).toLocaleString() + " g of saturated fat <br />")
    .append((Math.round(stocks[index][8] * amt * 100)/100).toLocaleString() + " g of sugar <br />")
    .append((Math.round(stocks[index][10] * amt * 100)/100).toLocaleString() + " mg of sodium <br />")
    .append((Math.round(stocks[index][11] * amt * 100)/100).toLocaleString() + " mg of cholesterol <br />") 
    .append((Math.round(stocks[index][12] * amt * 100)/100).toLocaleString() + " mg of vitamin D<br />")
    .append((Math.round(stocks[index][13] * amt * 100)/100).toLocaleString() + " mg of vitamin C<br />")
    .append((Math.round(stocks[index][14] * amt * 100)/100).toLocaleString() + " mg of Calcium<br />")
    .append((Math.round(stocks[index][15] * amt * 100)/100).toLocaleString() + " mg of Zinc<br />")
    .append("$"+(Math.round(stocks[index][16] * amt * 100)/100).toLocaleString() + " in average costs<br />");
  });
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<head>
  <meta name="viewport" content="width=10px, initial-scale=1.0">
</head>

<body>

  <input value = "" type="text" id="numberOfStocks" />
  <div style="display:block;">
    <div class="side">
      <h2>serving of: </h2>
    <select class="selectStock">
      <option>Pick a food!</option>
    </select>
    <br>
    <br>
    <div class="result"></div>
    </div>
    <div class="side">
      <h2>vs serving of:</h2>
    <select class="selectStock">
      <option>Pick a food!</option>
    </select>

    <br>
    <br>
    <div class="result"></div>
</div>
  </div>
</body>

Everything is working and things look good, but instead of outputting the values of the arrays I need to output a column that displays the difference between the values- ie. "4.3 less grams of protein" between food A and food B. I'd also need the values of the foods to not be shown as well.

I've tried creating this Comparison column, but everytime I try to modify the code it doesn't display any values. Really appreciate the help!