accept-reject.js

// Acceptance rejection technique
function AcceptReject() {}

AcceptReject.prototype.inverseG = function(x) {
  return -1 * Math.log((1 - x) / 2.85);
};

AcceptReject.prototype.f = function(x) {
  return 20 * x * Math.pow(1 - x, 3);
};

AcceptReject.prototype.g = function(x) {
  return 2.85 * Math.pow(Math.E, -x);
};

AcceptReject.prototype.genX = function(){
  var u, x, v, gx, fx;
  var iterations = 0;
  do {
    u = Math.random();
    v = Math.random();
    x = this.inverseG(u);
    gx = this.g(x);
    fx = this.f(x);
    iterations++;
  } while((1 * gx * v) > fx);

  console.log('x: ' + x, 'interations: ' + iterations);
};

var runner = new AcceptReject();

for (var i = 0; i < 10; i++) {
  runner.genX();
}