paypal-jquery.js

paypal.Button.render({

    payment: function() {
        return jQuery.ajax({
            method: 'POST',
            url:    '/generate-paypal-token'        
        }).then(function(data, status, res) {

            // Reject the promise if token not returned
            if (!data.token) {
                throw new Error('Response did not contain a PayPal token');
            }

            // Reject the promise if non-200 response code
            if (res.status !== 200) {
                throw new Error('Response non-200 code: ' + res.status);
            }

            // Otherwise resolve the promise with the token
            return data.token;
        });
    },

    onAuthorize: function(data, actions) {

        // Redirect to the return URL
        return actions.redirect();
    },
  
    onCancel: function(data, actions) {

        // Redirect to the cancel URL
        return actions.redirect();
    },

    onError: function(err) {
        // Handle errors here; show an error message or redirect to an error page
        // Note: any rejected promise from the `payment()` function will call this error handler
    }

}, '#container');