.env file in the Glitch app under WHATSAPP\_TOKEN..env variable called VERIFY\_TOKEN. This can be any string you choose. In our case, we picked "blue\_panda"..env file in the Glitch app will look like this: 
/webhook to the end of the URL. 
blue\_panda in our case): 
Before you start, make sure to register and sign into an AWS development account.
In AWS:
us-east-1 region. So the actual link is . Click Create Function > Author from scratch and create your function. For this example, we have added and/or selected the following options:
cloudEchoNode.js 16.x, since we're implementing Javascript-based Lambda functionCreate a new role with basic Lambda permissionsEnable function URL has been checked and Auth type was set to None.
The Advanced Settings look like this:
Once the function is created, you are redirected to the function page. There, you can see the following information:
.lambda-url.AWS\_REGION.on.aws/. Save that for later use.Inside your function's Code Source, you need to add code that does the following:
GET and POST requestsGETrequest described here.The code sample to be copied and pasted is:
const https = require("https"); |
exports.handler = async (event) => {
const VERIFY\_TOKEN = "Set\_your\_verify\_token\_value\_here";
const WHATSAPP\_TOKEN = "Paste\_whatsapp\_access\_token\_here";
let response;
if (event?.requestContext?.http?.method === "GET") {
//
// to learn more about GET request for webhook verification
let queryParams = event?.queryStringParameters;
if (queryParams != null) {
const mode = queryParams\["hub.mode"];
if (mode == "subscribe") {
const verifyToken = queryParams\["hub.verify\_token"];
if (verifyToken == VERIFY\_TOKEN) {
let challenge = queryParams\["hub.challenge"];
response = {
"statusCode": 200,
"body": parseInt(challenge),
"isBase64Encoded": false
};
} else {
const responseBody = "Error, wrong validation token";
response = {
"statusCode": 403,
"body": JSON.stringify(responseBody),
"isBase64Encoded": false
};
}
} else {
const responseBody = "Error, wrong mode";
response = {
"statusCode": 403,
"body": JSON.stringify(responseBody),
"isBase64Encoded": false
};
}
}
else {
const responseBody = "Error, no query parameters";
response = {
"statusCode": 403,
"body": JSON.stringify(responseBody),
"isBase64Encoded": false
};
}
} else if (event?.requestContext?.http?.method === "POST") {
// process POST request (WhatsApp chat messages)
//
// to learn about WhatsApp text message payload structure
let body = JSON.parse(event.body)
let entries = body.entry;
for (let entry of entries) {
for (let change of entry.changes) {
let value = change.value;
if(value != null) {
let phone\_number\_id = value.metadata.phone\_number\_id;
if (value.messages != null) {
for (let message of value.messages) {
if (message.type === 'text') {
let from = message.from;
let message\_body = message.text.body;
let reply\_message = "Ack from AWS lambda: " + message\_body;
sendReply(phone\_number\_id, WHATSAPP\_TOKEN, from, reply\_message);
const responseBody = "Done";
response = {
"statusCode": 200,
"body": JSON.stringify(responseBody),
"isBase64Encoded": false
};
}
}
}
}
}
}
} else {
const responseBody = "Unsupported method";
response = {
"statusCode": 403,
"body": JSON.stringify(responseBody),
"isBase64Encoded": false
};
}
return response;
}
const sendReply = (phone\_number\_id, whatsapp\_token, to, reply\_message) => {
let json = {
messaging\_product: "whatsapp",
to: to,
text: { body: reply\_message },
};
let data = JSON.stringify(json);
let path = "/v12.0/"+phone\_number\_id+"/messages?access\_token="+whatsapp\_token;
let options = {
host: "graph.facebook.com",
path: path,
method: "POST",
headers: { "Content-Type": "application/json" }
};
let callback = (response) => {
let str = "";
response.on("data", (chunk) => {
str += chunk;
});
response.on("end", () => {
});
};
let req = https.request(options, callback);
req.on("error", (e) => {});
req.write(data);
req.end();
} In Meta for Developers:
In AWS:
VERIFY\_TOKEN field in your Lambda function. For this example, we're using blue\_panda. 
In Meta for Developers:
blue\_panda): 
messages object. Then, click Done.