Wave Pay Mini App

Wave Pay Mini App (Wave Money JS SDK v1.8) lets the customer pay inside the WavePay app: your web page runs in the app's webview and calls Wave's JavaScript SDK. Your server covers the three parts that need secrets; the page itself calls makePayment.

Call	What it does	Returns
`await miniApp.accessToken()`	Get an access token for the page, cached	`string`
`miniApp.payment(data)`	Sign the `makePayment` payload, no API call	`MiniAppPayment`
`miniApp.handleCallback(request, callbackUrl)`	Verify the callback	`PaymentCallback`

Wave Pay Mini App has no status API: the callback is the only payment result.

How it works

The page logs in with a token from your server, then pays with a payload your server signed. Wave posts the result to your callback URL.

Wave Pay Mini App: token, signed payment, result

Configuration

import {
  WavePayMiniApp,
  WavePayMiniAppConfig,
} from '@laranex/myanmar-payments/wave-pay-mini-app';

// Create it once at startup: the in-memory token cache lives on the instance.
const miniApp = new WavePayMiniApp(
  {
    clientId: '...',
    clientSecret: '...',
    miniAppId: '...',
    secretKey: '...',
    baseUrl: WavePayMiniAppConfig.PRODUCTION_URL,
  },
  { tokenCache }, // optional: a shared TokenCache
);
// or WavePayMiniApp.fromEnv(process.env, { tokenCache }), or payments.wavePayMiniApp()

Variable	Option	Description
`WAVE_PAY_MINI_APP_CLIENT_ID`	`clientId`	Client ID issued by Wave, for the token endpoint
`WAVE_PAY_MINI_APP_CLIENT_SECRET`	`clientSecret`	Client secret issued by Wave, for the token endpoint
`WAVE_PAY_MINI_APP_MINI_APP_ID`	`miniAppId`	Your mini app ID (`miniAppID`)
`WAVE_PAY_MINI_APP_SECRET_KEY`	`secretKey`	Hash secret key for payment and callback hashes
`WAVE_PAY_MINI_APP_BASE_URL`	`baseUrl`	The API base URL, e.g. `WavePayMiniAppConfig.PRODUCTION_URL`. A trailing `/` is dropped
`MYANMAR_PAYMENTS_HTTP_TIMEOUT`	`timeoutSeconds`	Optional, 30 seconds by default

Every setting except the timeout is required. See Configuration for the production and UAT base URLs.

Access Token

The page needs an access token for WaveJsSDK.authModule.loginWithAccessToken(token). Return await miniApp.accessToken() from an endpoint of your own:

// GET /mini-app/token
res.writeHead(200, { 'Content-Type': 'application/json' });
res.end(JSON.stringify({ accessToken: await miniApp.accessToken() }));

accessToken() posts client_id, client_secret and grant_type=client_credentials as a form to {baseUrl}/auth/v1/external-utility/token and returns access_token. The token is kept in the token cache under myanmar-payments.wave-pay-mini-app.token.<sha256 of baseUrl|clientId>, the same key in every Laranex SDK, for Wave's expires_in minus 60 seconds (at least 60 seconds; expires_in is read from its leading digits, and a missing or non-positive value means 3600). Concurrent calls share one token request, bounded by the HTTP client timeout rather than one call's signal, so aborting one call never fails the others. await miniApp.forgetToken() drops the cached token. Never request the token from the browser: it needs the client secret.

Starting a Payment

import type { WavePayMiniAppPaymentData } from '@laranex/myanmar-payments/wave-pay-mini-app';

const data: WavePayMiniAppPaymentData = {
  orderId: `ORDER_${order.id}`,
  callbackUrl: 'https://shop.test/payments/wave-pay-mini-app/callback',
  items: [
    { name: 'Ticket', amount: 3000 },
    { name: 'Snack', amount: 2000 },
  ],
};

const payment = miniApp.payment(data);

// Store data.merchantReferenceId with the order: payment() filled it in.

res.writeHead(200, { 'Content-Type': 'application/json' });
res.end(payment.toJsonString());

payment() sends no request: it validates the data, signs the payload and returns it.

WavePayMiniAppPaymentData

Field	Type	Required	Rules
`orderId`	`string`	Yes	Your order ID (`orderID`)
`callbackUrl`	`string`	Yes	Absolute http or https URL that Wave posts the result to (`callBackUrl`). It is signed, so verify the callback with this same URL
`items`	`WavePayMiniAppItem[]`	Yes	At least one item
`amount`	`Amount \| number \| bigint`	No	Whole kyat, greater than 0 (Wave doesn't accept decimals). Unset or `null` charges the exact sum of the items
`merchantReferenceId`	`string`	No	Your ID for this attempt (`merchantRefID`). Unset or empty means a random 32-character hex ID, written back to `data.merchantReferenceId`

WavePayMiniAppItem has a name (required) and an amount in whole kyat, greater than 0. The items are summed with exact bigint arithmetic; WavePayMiniApp.resolvedAmount(data) returns the total that will be charged. WavePayMiniApp.validate(data) collects errors in this order: orderId, callbackUrl, items, merchantReferenceId, each item's items.0.name and items.0.amount, then amount. Without items or amount, amount reports The amount field is required.; a negative amount reports The amount field must not be negative.; a decimal one reports Wave Pay Mini App does not accept decimal amounts; the amount field must be a whole number. Invalid data is left untouched.

The makePayment Payload

JSON.stringify(payment) (through payment.toJSON()) is exactly the object Wave's makePayment takes, in this order:

json

{
  "amount": 5000,
  "miniAppID": "MINI456",
  "merchantRefID": "3f9c0d6e5b2a41c8a7e1f0b9d4c3a2e1",
  "orderID": "ORDER_1",
  "callBackUrl": "https://shop.test/payments/wave-pay-mini-app/callback",
  "hashValue": "…",
  "items": [
    { "name": "Ticket", "amount": 3000 },
    { "name": "Snack", "amount": 2000 }
  ]
}

Amounts are JSON integers. hashValue is the lowercase hex HMAC-SHA256, keyed with the secret key, of amount, orderID, miniAppID, merchantRefID and callBackUrl joined with no separator, e.g. 5000ORDER123MINI456MERCHANT789https://yourdomain.com/callback. An amount above Number.MAX_SAFE_INTEGER is written with every digit through JSON.rawJSON (Node.js 21+; older versions throw a RangeError); payment.toJsonString() writes every digit on every Node.js version.

On the Page

Load Wave's SDK as Wave's guide shows, then pass the payload from your server unchanged. Never compute the token or the hash in the browser.

const sdk = new WaveJsSDK({ appName: 'My Shop', appIconUrl: 'https://shop.test/icon.png' })
await sdk.init()

const { accessToken } = await (await fetch('/mini-app/token')).json()
await window.WaveJsSDK.authModule.loginWithAccessToken(accessToken)

const payload = await (await fetch('/mini-app/orders/1/pay', { method: 'POST' })).json()
const result = await window.WaveJsSDK.paymentModule.makePayment(payload)

makePayment's result only tells the page how the payment screen ended; fulfill from the verified callback.

Merchant Reference ID

Give every attempt, including a retry of the same order, a new merchantReferenceId. Leave it empty to get a fresh random ID, and store it after payment(): the callback's merchantRefId tells you which attempt was paid.

Handling Callbacks

The callback carries neither the mini app ID nor the callback URL, so pass the callback URL the payment was signed with: normally the URL the callback was posted to, without its query string. The mini app ID comes from the configuration.

import { CallbackRequest } from '@laranex/myanmar-payments';

// POST /payments/wave-pay-mini-app/callback
try {
  const request = await CallbackRequest.fromNodeRequest(req);
  const callback = miniApp.handleCallback(
    request,
    'https://shop.test/payments/wave-pay-mini-app/callback',
  );

  if (callback.isSuccessful()) {
    // callback.orderId is your orderId
    // callback.raw.merchantRefId is the attempt's reference
    // callback.gatewayReference is Wave's transactionId
  }

  callback.acknowledgement.send(res);
} catch {
  res.writeHead(400).end('invalid callback');
}

The expected hashValue is the same HMAC as the payment's, over the callback's amount (its exact JSON text), orderId, your mini app ID, merchantRefId and the callback URL you pass, compared in constant time and ignoring the case of the hex digits. A missing or non-string hashValue, a mismatch, or an object or array in any callback field throws SignatureVerificationError with Wave Pay Mini App callback hash verification failed.. After the hash matches, orderId and merchantRefId must not be empty and amount must be a whole number; otherwise it throws Wave Pay Mini App callback is malformed..

Statuses

Only successful means the customer paid. transactionStatus is matched trimmed and case-insensitively.

Wave `transactionStatus`	`PaymentStatus`
`successful`	`successful`
`processing`	`pending`
`failed`	`failed`
anything else	`unknown`

Responses

See Results and PaymentCallback & Status for the full classes.

`payment()` → `MiniAppPayment`

Field / Method	Wave Pay Mini App value
`flow`	`'mini_app'`
`orderId`	Your `data.orderId`
`amount`	The signed total, an `Amount` in whole kyat
`miniAppId`	The configured mini app ID
`merchantReferenceId`	Your `data.merchantReferenceId`, generated when empty
`callbackUrl`	Your `data.callbackUrl`
`hashValue`	The payload's hash
`items`	`readonly MiniAppPaymentItem[]`: `{ name, amount }`, `amount` an `Amount`
`toJSON()`	The `makePayment` object (`MiniAppPaymentPayload`): `amount`, `miniAppID`, `merchantRefID`, `orderID`, `callBackUrl`, `hashValue`, `items` (`name`, `amount`), amounts as numbers
`toJsonString()`	The same object as compact JSON, amounts with every digit

`handleCallback()` → `PaymentCallback`

Field	Wave Pay Mini App value
`orderId`	Wave `orderId`
`status`	`transactionStatus` mapped, see Statuses
`gatewayStatus`	Wave `transactionStatus`, trimmed, e.g. `successful`
`gatewayReference`	Wave `transactionId`
`amount`	Wave `amount`, e.g. `1000`
`raw`	The verified body: `merchantRefId`, `orderId`, `amount`, `msisdn`, `hashValue`, `transactionId`, `transactionStatus`
`acknowledgement`	HTTP `200`, empty body, `Content-Type: text/plain`

Errors

Call	Throws	When
`new WavePayMiniAppConfig(...)`	`ConfigurationError`	A setting is missing or blank, e.g. `The wave_pay_mini_app configuration is missing [client_id].`
`payment()`	`InvalidPaymentDataError`	`WavePayMiniApp.validate(data)` fails. Nothing is signed and `data` is left untouched. Item errors use `items.0.name` and `items.0.amount` keys
`accessToken()`	`ApiError`	Wave answers with an HTTP error, a body that isn't JSON, or no `access_token`. The message is `Wave Pay Mini App token request failed: [<error>] <error_description>` when Wave sends an `error`, else `Wave Pay Mini App token request failed with HTTP <status>.`; `gatewayCode` is Wave's `error`, `gatewayMessage` its `error_description` (or `message`)
`handleCallback()`	`SignatureVerificationError`	`Wave Pay Mini App callback hash verification failed.`: `hashValue` is missing, not a string or doesn't match, or a callback field holds an object or array. `Wave Pay Mini App callback is malformed.`: the hash matched but `orderId` or `merchantRefId` is empty, or `amount` isn't a whole number

When Wave can't be reached, accessToken() throws ApiError with httpStatus 0 and the original error as cause.

Wave Pay Mini App ​

How it works ​

Configuration ​

Access Token ​

Starting a Payment ​

WavePayMiniAppPaymentData ​

The makePayment Payload ​

On the Page ​

Merchant Reference ID ​

Handling Callbacks ​

Statuses ​

Responses ​

payment() → MiniAppPayment ​

handleCallback() → PaymentCallback ​

Errors ​