Category: JavaScript Answers

Sometimes, we want to add error handling to Node.js streams.

In this article, we’ll look at how to add error handling to Node.js streams.

How to add error handling to Node.js streams?

To add error handling to Node.js streams, we call pipeline with all the operators before the error handler.

For instance, we write

const {
  pipeline,
  finished
} = require('stream');

pipeline(
  input,
  transformA,
  transformB,
  transformC,
  (err) => {
    if (err) {
      console.error('Pipeline failed', err);
    } else {
      console.log('Pipeline succeeded');
    }
  });


finished(input, (err) => {
  if (err) {
    console.error('Stream failed', err);
  } else {
    console.log('Stream is done reading');
  }
});

to call pipeline with the operators input, transformA, and transformB, and transformC.

Then we pass in the error handler callback so that errors with any of the operators will be picked up by it.

Then we call finished with input to handle any errors with input.

Conclusion

To add error handling to Node.js streams, we call pipeline with all the operators before the error handler.

Sometimes, we want to remove menu bar from Electron app.

In this article, we’ll look at how to remove menu bar from Electron app.

How to remove menu bar from Electron app?

To remove menu bar from Electron app, we can set the autoHideMenuBar to true.

For instance, we write

const mainWindow = new BrowserWindow({
  autoHideMenuBar: true,
})

to create a BrowserWindow instance by passing in an object with autoHideMenuBar set to true.

As a result, the menu bar would be hidden in the app.

Conclusion

To remove menu bar from Electron app, we can set the autoHideMenuBar to true.

Sometimes, we want to restart Node upon changing a file.

In this article, we’ll look at how to restart Node upon changing a file.

How to restart Node upon changing a file?

To restart Node upon changing a file, we can use the supervisor package.

We install it by running

npm install supervisor -g

Then we can watch for file changes in the Node project with entry point app.js by running

supervisor app.js

Conclusion

To restart Node upon changing a file, we can use the supervisor package.

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

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

How to move files in Node.js?

To move files in Node.js, we can use the fs.rename method.

For instance, we write

const fs = require('fs')

const oldPath = 'old/path/file.txt'
const newPath = 'new/path/file.txt'

fs.rename(oldPath, newPath, (err) => {
  if (err) {
    throw err
  }
  console.log('successfully moved')
})

to call rename with the oldPath of the file, newPath of the file, and a callback that runs when the moving is done.

If there’s an error, err will be set.

Conclusion

To move files in Node.js, we can use the fs.rename method.

Sometimes, we want to read a text file into an array with each line an item in the array.

In this article, we’ll look at how to read a text file into an array with each line an item in the array.

How to read a text file into an array with each line an item in the array?

To read a text file into an array with each line an item in the array, we can use the readFileSync or readFile method.

For instance, we write

const fs = require('fs');

const array = fs.readFileSync('file.txt').toString().split("\n");
for (const a of array) {
  console.log(a);
}

to call fs.readFileSync to read 'file.txt' synchronously.

Then we call toString to return the read file as a string.

And then we split the string into an array with each line as an item with split.

Then we loop through each array entry with the for-of loop.

We call readFile to read the file asynchronously.

To use it, we write

const fs = require('fs');

fs.readFile('file.txt', (err, data) => {
  if (err) {
    throw err;
  }
  
  const array = data.toString().split("\n");
  for (const a of array) {
    console.log(a);
  }
});

to call readFile to read 'file.txt'.

The callback is run when the file is read.

And we convert the file to a string, split the lines, and loop through them the same way.

Conclusion

To read a text file into an array with each line an item in the array, we can use the readFileSync or readFile method.