Creating two dimensional array for x, y using D3.Range and use them to create y axis

I am using D3.js to create a very smooth curve and therefore I used d3.range(starts, stops,steps) function to accomplish that. Also I had to use a specific formula to generate numbers for y axis with the following code:

  d3.json("sample-data.json",returnLineData);

 function returnLineData(error,jsonData)
        {
            console.log("error:",error);
           /* console.log(jsonData);*/

            jsonData.forEach(function(jsonData){
                 var lineData = d3.range(0, jsonData.spend, 100)
                        .map(x => [ x, jsonData.alpha * (1 - 2.71828 * (-jsonData.beta * x))] );
                       /*  console.log("this is the data:",lineData);*/

                    Metrics.push(lineData);
            }) 
        }

As a result I will get the following result. I attached the initial look of the array structure as a screenshot and pasting some sample generated data. I tried to name the first index as X and the second index as Y with the code below:

 Metrics.push({x:lineData[0],
               y:lineData[1]}); 

But it would appear very weird. So how can I use the numbers which increments by 100 as X and the decimals as Y?

enter image description here

(2) [0, 140]
1
:
(2) [100, 141.468958512]
2
:
(2) [200, 142.937917024]
3
:
(2) [300, 144.406875536]
4
:
(2) [400, 145.875834048]
5
:
(2) [500, 147.34479256]
6
:
(2) [600, 148.813751072]
7
:
(2) [700, 150.282709584]
8
:
(2) [800, 151.751668096]
9
:
(2) [900, 153.22062660799998]
10
:
(2) [1000, 154.68958512]
11
:
(2) [1100, 156.158543632]
12
:
(2) [1200, 157.627502144]

The original data before the formula is below:

[
  {
    "placement_name": "BAN_1",
    "alpha": 140,
    "beta": 0.0000386,
    "max_x_val": 28675,
    "spend": 29919
  },
  {
    "placement_name": "BAN_2",
    "alpha": 115,
    "beta": 0.0000208,
    "max_x_val": 32302,
    "spend": 28367
  },
  {
    "placement_name": "BAN_3",
    "alpha": 91.9,
    "beta": 0.0000507,
    "max_x_val": 19740,
    "spend": 16972
  },
  {
    "placement_name": "ADJ_4",
    "alpha": 91.8,
    "beta": 0.000029119,
    "max_x_val": 25855,
    "spend": 27112
  },
  {
    "placement_name": "ADJ_5",
    "alpha": 90.3,
    "beta": 0.0000281,
    "max_x_val": 25793,
    "spend": 23883
  },
  {
    "placement_name": "ADJ_6",
    "alpha": 88.8,
    "beta": 0.0000178,
    "max_x_val": 25263,
    "spend": 28401
  },
  {
    "placement_name": "ADJ_7",
    "alpha": 47.3,
    "beta": 0.000100787,
    "max_x_val": 10226,
    "spend": 12428
  },
  {
    "placement_name": "ADJ_8",
    "alpha": 47.3,
    "beta": 0.0000254,
    "max_x_val": 25669,
    "spend": 21899
  },
  {
    "placement_name": "ADJ_9",
    "alpha": 44,
    "beta": 0.00018458,
    "max_x_val": 6928,
    "spend": 9068
  }
]