From Let's Grow Mushrooms

Main: Paypal-Smart-Buttons

<div id="smart-button-container">

      <div style="text-align: center;">
        <div id="paypal-button-container"></div>
      </div>
    </div>
  <script src="https://www.paypal.com/sdk/js?client-id=sb&currency=USD" data-sdk-integration-source="button-factory"></script>
  <script>
    function initPayPalButton() {
      paypal.Buttons({
        style: {
          shape: 'pill',
          color: 'gold',
          layout: 'vertical',
          label: 'paypal',

        },

        createOrder: function(data, actions) {
          return actions.order.create({
            purchase_units: [{"description":"Download Let's Grow Mushrooms!","amount":{"currency_code":"USD","value":8.99}}]
          });
        },

        onApprove: function(data, actions) {
          return actions.order.capture().then(function(details) {
            alert('Transaction completed by ' + details.payer.name.given_name + '!');
          });
        },

        onError: function(err) {
          console.log(err);
        }
      }).render('#paypal-button-container');
    }
    initPayPalButton();
  </script>