Category: JavaScript Answers

Sometimes, we want to throttle and queue up API requests due to per second cap with Node.js.

In this article, we’ll look at how to throttle and queue up API requests due to per second cap with Node.js.

How to throttle and queue up API requests due to per second cap with Node.js?

To throttle and queue up API requests due to per second cap with Node.js, we can use the node-rate-limiter package.

To install it, we run

npm i limiter

Then we use it by writing

const { RateLimiter } = require("limiter");

const limiter = new RateLimiter({ tokensPerInterval: 150, interval: "hour" });
const throttledRequest = async (...args) => {
  const remainingRequests = await limiter.removeTokens(1);
  callMyMessageSendingFunction(...args);
};

to create a RateLimiter instance with { tokensPerInterval: 150, interval: "hour" } to allow 150 requests her hour.

Then we create the throttledRequest function that calls limiter.removeTokens with 1 and a callback that calls callMyMessageSendingFunction to return a function that throttles the request calls to 150 her hour.

Conclusion

To throttle and queue up API requests due to per second cap with Node.js, we can use the node-rate-limiter package.

Sometimes, we want to get the path from the request with Node.js.

In this article, we’ll look at how to get the path from the request with Node.js.

How to get the path from the request with Node.js?

To get the path from the request with Node.js, we can use the request.url property.

For instance, we write

const http = require("http");
const url = require("url");

const start = () => {
  const onRequest = (request, response) => {
    const { pathname } = url.parse(request.url);
    console.log(pathname);
    response.writeHead(200, { "Content-Type": "text/plain" });
    response.write("Hello World");
    response.end();
  };
  http.createServer(onRequest).listen(8888);
};

start();

to get the request.url from the request.

Then we call url.parse to parse it to return an object with the pathname to get the request URL path.

Conclusion

To get the path from the request with Node.js, we can use the request.url property.

Sometimes, we want to configure axios to use SSL certificate.

In this article, we’ll look at how to configure axios to use SSL certificate.

How to configure axios to use SSL certificate?

To configure axios to use SSL certificate, we set the rejectUnauthorized option to false and add our certificate files as the options for axios.

For instance, we write

const httpsAgent = new https.Agent({
  rejectUnauthorized: false,
  cert: fs.readFileSync("./usercert.pem"),
  key: fs.readFileSync("./key.pem"),
  passphrase: "YYY",
});

axios.get(url, { httpsAgent });

to create the httpsAgent object with the https.Agent constructor.

We set rejectUnauthorized to disable client verification.

And then we add the certificate and private keys by setting the files as the values of cert and key respectively.

We also set the passphrase for the certificate if we have one.

Then we call axios.get or other request methods with httpsAgent in the option object.

We can also create a new axios instance with the httpsAgent with

const instance = axios.create({ httpsAgent });

Conclusion

To configure axios to use SSL certificate, we set the rejectUnauthorized option to false and add our certificate files as the options for axios.

Sometimes, we want to create a Node.js server that accepts POST requests.

In this article, we’ll look at how to create a Node.js server that accepts POST requests.

How to create a Node.js server that accepts POST requests?

To create a Node.js server that accepts POST requests, we can use the http module.

For instance, we write

const http = require("http");
const server = http.createServer((request, response) => {
  response.writeHead(200, { "Content-Type": "textplain" });
  if (request.method === "GET") {
    response.end("received GET request.");
  } else if (request.method === "POST") {
    response.end("received POST request.");
  } else {
    response.end("Undefined request .");
  }
});

server.listen(8000);
console.log("Server running on port 8000");

to call http.createServer with a callback to create a web server.

We call it with a callback that receives the request.

If request.method is 'POST', then a POST request is received.

And then we call response.end to return a response body string.

Conclusion

To create a Node.js server that accepts POST requests, we can use the http module.

Sometimes, we want to use the Mongoose use of select method in Node.js.

In this article, we’ll look at how to use the Mongoose use of select method in Node.js.

How to use the Mongoose use of select method in Node.js?

To use the Mongoose use of select method in Node.js, we can use the find method with the fields we want to return in the results.

For instance, we write

User.find({}, "first last", (err, user) => {
  //...
});

to call User.find with 'first last' to get the User results and return the first and last properties in each result only.

We get the returned query results from the user parameter.

Conclusion

To use the Mongoose use of select method in Node.js, we can use the find method with the fields we want to return in the results.