window.onload = function() {
  document.body.className = 'ready';
}; 

(function() {
  var viewPurchasePage = function() {
    location.href = 'purchase.html'
  };

  document.getElementById('btn1').onclick = function() {
    location.href = 'purchase/express'
  };

  document.getElementById('btn2').onclick = function() {
    location.href = 'purchase/standard'
  };

  document.getElementById('btn3').onclick = function() {
    location.href = 'purchase'
  };

  document.getElementById('btn4').onclick = function(){
    location.href = '/mall/shoplist'
  };
})();