diff --git a/paymentrequest/index.d.ts b/paymentrequest/index.d.ts
index d3a362d401..50ef94e1e6 100644
--- a/paymentrequest/index.d.ts
+++ b/paymentrequest/index.d.ts
@@ -27,7 +27,7 @@ interface PaymentDetails {
     total: PaymentItem;
     displayItems?: PaymentItem[];
     shippingOptions?: PaymentShippingOption[];
-    modifiers: PaymentDetailsModifier[];
+    modifiers?: PaymentDetailsModifier[];
 }
 
 interface PaymentDetailsModifier {
diff --git a/paymentrequest/tests.ts b/paymentrequest/tests.ts
new file mode 100644
index 0000000000..db74be2a21
--- /dev/null
+++ b/paymentrequest/tests.ts
@@ -0,0 +1,106 @@
+/// <reference path="index.d.ts" />
+/// <reference path="../promise" />
+
+function makeRequest() {
+    if (!window.PaymentRequest) {
+        return Promise.reject(new Error("PaymentRequest not available"))
+    }
+
+    const methodData = [
+        {
+            supportedMethods: ["visa", "mastercard"]
+        }
+    ]
+
+    const details = {
+        displayItems: [
+            {
+                label: "Original donation amount",
+                amount: { currency: "USD", value : "65.00" }, // US$65.00
+            },
+            {
+                label: "Friends and family discount",
+                amount: { currency: "USD", value : "-10.00" }, // -US$10.00
+            }
+        ],
+        total:  {
+            label: "Total",
+            amount: { currency: "USD", value : "55.00" }, // US$55.00
+        }
+    }
+
+    const options = {
+        requestShipping: true,
+        requestPayerEmail: true,
+        requestPayerPhone: true
+    }
+
+    const request = new window.PaymentRequest(methodData, details, options)
+    request.addEventListener("shippingaddresschange", onShippingAddressChange)
+
+    return request.show()
+}
+
+async function processPayment() {
+    try {
+        const paymentResponse = await makeRequest()
+    } catch (error) {
+        location.href = '/checkout';
+        return;
+    }
+
+    var paymentData = {
+        // payment method string
+        method: paymentResponse.methodName,
+        // payment details as you requested
+        details: paymentResponse.details,
+        // shipping address information
+        address: toDict(paymentResponse.shippingAddress),
+        // shipping option
+        shippingOption: paymentResponse.shippingOption
+    }
+
+    // make call to backend to process payment data
+    const ok = await Promise.resolve(true)
+
+    if (ok) {
+        paymentResponse.complete("success")
+    } else {
+        paymentResponse.complete("fail")
+    }
+}
+
+function onShippingAddressChange(e) {
+    e.updateWith(((details, addr) => {
+        if (addr.country === 'US') {
+            var shippingOption = {
+                id: '',
+                label: '',
+                amount: {currency: 'USD', value: '0.00'},
+                selected: true
+            };
+            if (addr.region === 'US') {
+                shippingOption.id = 'us';
+                shippingOption.label = 'Standard shipping in US';
+                shippingOption.amount.value = '0.00';
+                details.total.amount.value = '55.00';
+            } else {
+                shippingOption.id = 'others';
+                shippingOption.label = 'International shipping';
+                shippingOption.amount.value = '10.00';
+                details.total.amount.value = '65.00';
+            }
+            if (details.displayItems.length === 2) {
+                details.displayItems.splice(1, 0, shippingOption);
+            } else {
+                details.displayItems.splice(1, 1, shippingOption);
+            }
+            details.shippingOptions = [shippingOption];
+        } else {
+            details.shippingOptions = [];
+        }
+        return Promise.resolve(details);
+    })(details, request.shippingAddress));
+}
+
+document.querySelector("#pay").addEventListener("click", processPayment)
diff --git a/paymentrequest/tsconfig.json b/paymentrequest/tsconfig.json
index 79b9eb6b27..55cf6b6d36 100644
--- a/paymentrequest/tsconfig.json
+++ b/paymentrequest/tsconfig.json
@@ -13,6 +13,7 @@
         "forceConsistentCasingInFileNames": true
     },
     "files": [
-        "index.d.ts"
+        "index.d.ts",
+        "tests.ts"
     ]
-}
\ No newline at end of file
+}