JSFiddle - React, Tailwind, and code Playground

JavaScript

var inc = .001;
  var z = new Array(1.0/inc);
  for (var x = 0.0; x < 1.0; x += inc) {
    z.push(Math.cos(x));
  }
  var y = new Array(1.0/inc);
  for (x = 0.0; x < 1.0; x += inc) {
    y.push(1 - ((x * x) / 2) + ((x * x * x * x) / 24));
  }
  var sum = 0;
  for (var i = 0; i < (1.0/inc); i++) {
    sum += y[x] - z[x];
  }
  console.log(sum);
  console.log(sum/(1.0/inc));