Find the minimum and maximum value in a series of data arrays (used with datavis plugins eg D3 to find axis ranges)

findMinMax.js

function findMinMax(arr, start) {
  var min = parseInt(start[0]) || parseInt(arr[0]);
  var max = parseInt(start[1]) || parseInt(arr[0]);
  
  for (let i = 0, len=arr.length; i < len; i++) {
    var v = parseInt(arr[i]);
    min = (v < min) ? v : min;
    max = (v > max) ? v : max;
  }

  return initial = [min, max];
}

var initial = [];
var data = [
  ["22", "20", "26", "25", "23", "22"],
  ["27", "28", "29", "37", "30", "27"],
  ["18", "22", "23", "22", "26", ""]
];

for (arrays in data) {
  findMinMax(data[arrays], initial)
}

console.log(initial);