Category: JavaScript Answers

Sometimes, we want to check synchronously if a file or directory exists in Node.js.

In this article, we’ll look at how to check synchronously if a file or directory exists in Node.js.

How to check synchronously if a file or directory exists in Node.js?

To check synchronously if a file or directory exists in Node.js, we can use the existsSync method.

For instance, we write

const fs = require("fs"); 
if (fs.existsSync(path)) {
  // ...
}

to call fs.existsSync with a path string to check if the path points to a valid file or folder.

It returns true if it does and false otherwise.

Conclusion

To check synchronously if a file or directory exists in Node.js, we can use the existsSync method.

Sometimes, we want to read environment variables in Node.js.

In this article, we’ll look at how to read environment variables in Node.js.

How to read environment variables in Node.js?

To read environment variables in Node.js, we can read them from the process.env property.

For instance, we write

const mode = process.env.NODE_ENV;

to read the NODE_ENV environment variable and assign it to mode.

Conclusion

To read environment variables in Node.js, we can read them from the process.env property.

Sometimes, we want to debug Node.js applications.

In this article, we’ll look at how to debug Node.js applications.

How to debug Node.js applications?

To debug Node.js applications, we can use the node-inspector package.

We install it with

npm install -g node-inspector

Then we run

node-debug app.js

to start app.js with the node-inspector debugger.

Conclusion

To debug Node.js applications, we can use the node-inspector package.

Sometimes, we want to write files in Node.js.

In this article, we’ll look at how to write files in Node.js.

How to write files in Node.js?

To write files in Node.js, we can use the fs.writeFile method.

For instance, we write

const fs = require('fs');

fs.writeFile("/tmp/test", "Hey there!", (err) => {
  if (err) {
    return console.log(err);
  }
  console.log("The file was saved!");
});

to call fs.writeFile with the path to write the file to, the file content string, and a callback that’s run when writeFile is finished running.

If there’s an error, then err will be set.

Conclusion

To write files in Node.js, we can use the fs.writeFile method.

Sometimes, we want to exit a Node.js program.

In this article, we’ll look at how to exit a Node.js program.

How to exit a Node.js program?

To exit a Node.js program, we can call process.exit.

For instance, we run

process.exit()

to exit the program without any exit code.

Or we can write

process.exit(1)

to exit the Node.js program with exit code 1.

Conclusion

To exit a Node.js program, we can call process.exit.