What is file descriptor in NodeJS?

What is file descriptor in NodeJS?

A file descriptor is a reference to an open file, a number (id) returned by opening the file using the open() method offered by the fs module. This number ( fd ) uniquely identifies an open file in operating system: JS copy.

How do I reduce the size of an image in node JS?

Explanation

1. await Jimp. read(imgPath) Reading the image.
2. resize(width, height) Resize the image with the given width but I don’t use height so the default value of Jimp.
3. quality(quality) Set a certain quality like 90%.
4. writeAsync(imgPath) Write the image without callback in an async way.

How do I process an image in node JS?

Project setup

1. Create a project directory named image-processing .
2. In the folder created above, run the command below to initialize Node. js in our project directory. $ npm init.
3. Run the command below to add JIMP package into our application. $ npm install –save jimp.
4. Create a file name index. js in the project directory.

How does FS read and write work in Node.js?

It’s a lower-level method, used internally by almost all Node.js methods related to FS read and write. Given the path, string of system flags, optional mode number and callback function it can create, read or recreate file that will later be available to read, write or whatever, depending on the passed arguments.

How to read a file in Node.js?

Possible encodings are ‘ascii’, ‘utf8’, and ‘base64’. If no encoding is provided, the default is null. callback is a function to call when the file has been read and the contents are ready – it is passed two arguments, error and data.

What does err stack do in Node.js?

This is a basic Node.js Error object – it can often be useful to log err.stack directly, since this contains a stack trace to the location in code at which the Error object was created.

When to pass a callback in Node.js?

Lastly, you need to pass a callback that always provides you with an error if something went wrong and nothing otherwise. Thus, if there’s no error thrown, you can be sure that you’ve got the correct access to the file. With the correct results of the access check, you can continue to read the file.