Category: JavaScript Answers

Sometimes, we want to check if Node.js writeFileSync successfully wrote the file.

In this article, we’ll look at how to check if Node.js writeFileSync successfully wrote the file.

How to check if Node.js writeFileSync successfully wrote the file?

To check if Node.js writeFileSync successfully wrote the file, we should wrap writeFileSync in a try-catch block.

For instance, we write

try {
  fs.writeFileSync(file, content, 'utf8');
} catch (e) {
  conso.e.log(e)
}

to call writeFileSync to write the content of the file to the file path with 'utf8' encoding.

If the write operation fails, an error will be thrown, and the error will be caught by the catch block.

Conclusion

To check if Node.js writeFileSync successfully wrote the file, we should wrap writeFileSync in a try-catch block.

Sometimes, we want to check if a request is http or https in Node.js.

In this article, we’ll look at how to check if a request is http or https in Node.js.

How to check if a request is http or https in Node.js?

To check if a request is http or https in Node.js, we can use the req.secure property in our middlewares.

req.secure is a shorthand for req.protocol === 'https'.

And if our app is behind a proxy, we need to enable 'trust proxy' so that req.protocol reflects the protocol that’s used to communicate between the client and proxy.

To enable it, we write

app.enable('trust proxy');

Conclusion

To check if a request is http or https in Node.js, we can use the req.secure property in our middlewares.

Sometimes, we want to create a sleep or delay in Node.js.

In this article, we’ll look at how to create a sleep or delay in Node.js.

How to create a sleep or delay in Node.js?

To create a sleep or delay in Node.js, we can create a function that returns a promise to pause execution for a specific amount of time.

For instance, we write

const sleep = (millis) => {
  return new Promise(resolve => setTimeout(resolve, millis));
}


const test = async () => {
  await sleep(1000)
  console.log("one second has elapsed")
}

to define the sleep function that returns a promise which calls setTimeout with resolve as a callback after millis milliseconds.

Then we call sleep in test with 1000 to pause the function for 1000 milliseconds and then call console.log to log "one second has elapsed".

Conclusion

To create a sleep or delay in Node.js, we can create a function that returns a promise to pause execution for a specific amount of time.

Sometimes, we want to use Sequelize findOne to find the latest entry.

In this article, we’ll look at how to use Sequelize findOne to find the latest entry.

How to use Sequelize findOne to find the latest entry?

To use Sequelize findOne to find the latest entry, we can use the findOne method with the order property to order items by createdAt descending.

For instance, we write

model.findOne({
  where: {
    key
  },
  order: [
    ['createdAt', 'DESC']
  ],
});

to call findOne with an object with the order property that’s set to an array with ['createdAt', 'DESC'] to order the results by the createdAt value sorted in descending order.

And we use where to return the result with key set to key.

Conclusion

To use Sequelize findOne to find the latest entry, we can use the findOne method with the order property to order items by createdAt descending.

Sometimes, we want to throttle the number of API requests per second in Node.js.

In this article, we’ll look at how to throttle the number of API requests per second in Node.js.

How to throttle the number of API requests per second in Node.js?

To throttle the number of API requests per second in Node.js, we can use the simple-rate-limiter package.

We install it by running

npm i simple-rate-limiter

Then we use it by writing

const limit = require("simple-rate-limiter");
const request = limit(require("request")).to(10).per(1000);

We call limit with the request module.

And we limit the number of requests to 10 per second with .to(10).per(1000).

Conclusion

To throttle the number of API requests per second in Node.js, we can use the simple-rate-limiter package.