从下拉菜单输出差异时获取空值？（Javascript）

我正在寻找建立一个简单的营养计算器，它可以计算一种食物和另一种食物之间的差异，然后输出营养事实的差异。有两件事我很难弄清楚：

代码似乎工作正常，但当我增加数量时，它返回NaN值，有时只计算为0

代码只能使用第一个文本框来链接值（两种食物都使用第一个文本框中的值，因此更改第二个文本框中的值不会起任何作用），我还无法计算出如何计算第一个文本框中的单位与另一个文本框中的单位之间的差异。我是否必须为第二种食物创建相同的功能 到目前为止，我掌握的代码是：

var股票=[
[“生牛肉（80/20）”，“盎司”，115.4451262,2.094125,1.199617347,72,4.85,5.65,0,2.142,19,20,0.000127510204,0.375,0.75,22.15988372,0.37682943,4]，
[“生牛肉（90/10）”，“盎司”，115.4451262,2.094125,1.199617347,50,5.65,2.83,0,1.109,19,18,0.000127510204,0.375,0.75,22.15988372,0.37682943,4]，
[“鸡胸肉”，“盎司”，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]，
[“鸡大腿/腿”，“盎司”，32.39053977,0.320375,0.07197704082125,2.72,12.54,0,3.431,14,30,0.01631172356,0.10625,0.2125,3.149953226,0.3765799405,4]，
[“牛奶（全脂）”，“液体盎司”，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]，
[“牛奶（2%），“液体盎司”，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]，
[“比萨饼（奶酪）”，“切片”，42,0.9700347449,0.006297991071285,12.19,10.37,3.83,4.778640,18,0.00001071428571,2.98828125,5.9765625,36.85985865,0.466697922,4]，
[“冰淇淋”，“杯子”，32.59312,0.6168324833,0.002345956329274.71344,4.6095984,14.4806576,27.9835216,8.94913952107.09168,55.87392,0.000003990994286,1.11311325,2.2262265,13.73003196,2.889031735,1]，
[“牛奶（脱脂）”，“液体盎司”，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]，
[“蛋（大）”，“每个”，43.13341461,0.514206,0.007354326122,78,6.29,5.3,0.2,1.633,62186,0.0016666667,0.265625,0.53125,3.713549,0.1305756192,1]，
[“羊羔肉”，“盎司”，78.125,2.8105,1.199617347,80,4.69,6.64,0,2.889,17,21,0.03333333,0.3125,0.625,2.274815967,0.3767295528,4]，
[“奶酪（硬）”，“切片（盎司）”，37.44571072,1.35025,0.002099330357105,6.59,8.41,0.14,5.32159,27,0.00000 3571428571,0.99609375,1.9921875,12.28661955,0.1303337926,1]，
[“酸奶”，“盎司”，5.833333333,0.09375,0.0002099330357,17,0.98,0.92,1.32,0.595,13,4,0.000000357142857142857,0.099609375,0.19921875,1.228661955,0.22294548,6]，
[“希腊酸奶，香草（脱脂）”，“液体盎司”，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]，
[“巧克力”，“盎司”，127.316,0.1862906,0.00004198660714151,2.16,8.39,14.57,5.238,22,7,0.0000000 714285714285714,0.019921875,0.03984375,1.601963425,1.345070603,1.45]，
[“可可”，“盎司”，179.739,0.625,0136,1.19,8.51,15.45,5.032,3,0,0,0,3.390577585,1.418619303,1.45]，
[“鲑鱼（养殖）”，“盎司”，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]，
[“金枪鱼（罐装油）”，“盎司”，0.498125,0.1197485281,0,56,8.26,2.33,0,0,0.435118,5,0.000270197828,1.0625,2.125,0.5593288054,0.3817664985,4]，
[“梅奥”，“盎司”，14.41309121,0.121875,0.001838581531193,0.27,21.22,0.16,3.318180,12,0.00041666667,0.06640625,0.1328125,0.92838725,0.1330741748,0.5]，
[“生拉猪肉”，“盎司”，44.84498316,0.63525,0.1411314526,53,4.94,3.5,0,1.232,17,18,0.000520833333,0.21875,0.4375,1.592371177,0.3767295528,4]，
[“黄油（盐渍）”，“盎司”，41.58720633,0.5875,0.00440859375203,0.24,22.95,0.02,14.537182,61,0.0000075,2.091796875,4.18359375,25.80190106,0.121322241,1]，
[“大豆汉堡”，“盎司”，21.8,0.048125,0,50,4.44,1.78,0.3,0.408161,1,0,0,0,2.314125,0.03342563782,4]，
[“纯素块金（大豆）”，“盎司”，21.8,0.048125,0,52,4.88,1.63,0.65,0.325172,0,0,0,0,2.314125,0.06360340429,4]，
[“豆浆（原味）”，“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]，
[“豆腐”，“盎司”，25.25,0.09625,0,23,2.82,1.49,0.2,0.26,1,0,0,0,4.62825,0.01698083545,4]，
[“坦佩”，“盎司”，12.383064,0.0230998152,0,54,5.74,3.06,0,0.719,3,0,0,0,0,1.110771114,0.0001496122504,4]，
[“混合坚果”，“盎司”，18.72285536,0.18425,0172,5.53,15.17,1.42,2.271,1,1,0,0,0,1.019662873,0.1202597201,1]，
[“面包”，“切片”，9.735884788,0.1530147137,0,79,3.09,1.31,1.66,0.202137,0,0,0,0,0.5625,0.1473592997,2]，
[“小扁豆”，“盎司”，30.3684714,0.07425,0,33,2.55,0.11,0.51,0.015,1,0,0,0,2.287814892,0.04322383072,7.1]，
[“黑豆”，“盎司”，30.3684714,0.141625,0,37,2.31,0.1,0.09,0.025,1,0,0,0,1.555714169,0.007668804863,7.1]，
[“番茄酱”，“盎司”，3.13704,0.09375,0,11,0.47,0.06,1.37,0.008,57,0,0,0,0,0,0,0.4188459746,0.1188197409,8]，
[“平托豆”，“盎司”，30.3684714,0.141625,0,40,2.55,0.18,0.09,0.038,0,0,0,0,0.9075003086,0.007618934113,7.1]，
[“炸薯条”，“盎司”，2.9337142,0.0417335921,0,56,0.82,1.91,0.14,0.359113,0,0,0,0,0.4200133922,0.01748707005,4]，
[“花生酱”，“盎司”，36,0.2145,0167,6.81,14.13,2.97,2.153138,0,0,0,3.675378676,0.25830693,1]，
[“橄榄油”，“盎司”，21.77842536,0.2306145384,0250,0,28.3,0,3.908,1,0,0,0,0,1.512500057,0.00004987075014,0.5]，
[“香蕉”，“1中等”，6.440662244,0.1763699536,0105,1.29,0.39,14.43,0.132,1,0,0,0,0,0.1768995697,1.221618974,1]，
[“混合蔬菜”，“盎司”，2.41150377,0.125,0,18,0.81,0.04,0,0.009,10,0,0,0,0,3,0.0004987075014,4]，
[“营养酵母”，“g”，0.08506329224,0.00706361088,0,3.9859577,0.5989518739,0,0,0,0,0,0,5]，
[“大米（白色）