Average distance of two random points in a square with side length 1

distance.js

function compute() {
  return distance(points());
}

function distance(points) {
  var deltaY = points[3] - points[1];
  var deltaX = points[2] - points[0];
  return Math.sqrt(Math.pow(deltaY, 2) + Math.pow(deltaX, 2));
}

function points() {
  return [
    Math.random(),
    Math.random(),
    Math.random(),
    Math.random()
  ]
}

var total = 0;

for (var i = 0; i<10000000; i++) {
  total += compute();
}

console.log(total / 10000000);