Author: John Au-Yeung

Sometimes, we want to get the full file path in Node.js.

In this article, we’ll look at how to get the full file path in Node.js.

How to get the full file path in Node.js?

To get the full file path in Node.js, we can use the path.resolve method.

For instance, we write

const path = require("path");
const absolutePath = path.resolve("/foo/bar/baz");

to call path.resolve with the relative path string to return the absolute path equivalent of the relative path.

Conclusion

To get the full file path in Node.js, we can use the path.resolve method.

Sometimes, we want to fix error when using "where" and "in" on a subarray with Node.js Sequelize.

In this article, we’ll look at how to fix error when using "where" and "in" on a subarray with Node.js Sequelize.

How to fix error when using "where" and "in" on a subarray with Node.js Sequelize?

To fix error when using "where" and "in" on a subarray with Node.js Sequelize, we can set the where property to an object with the properties being the fields we’re filtering by.

And we set the properties to arrays to search for the entries with any of the values.

For instance, we write

await Tag.findAll({
  where: {
    id: [1, 2, 3, 4]
  }
})

to call findAll with where.id set to [1, 2, 3, 4] to find the Tag items with id set to 1, 2, 3, or 4.

Conclusion

To fix error when using "where" and "in" on a subarray with Node.js Sequelize, we can set the where property to an object with the properties being the fields we’re filtering by.

And we set the properties to arrays to search for the entries with any of the values.

Sometimes, we want to load a Node.js module from string in memory.

In this article, we’ll look at how to load a Node.js module from string in memory.

How to load a Node.js module from string in memory?

To load a Node.js module from string in memory, we can use the require-from-string module.

To install it, we run

npm install require-from-string

Then we use it by writing

const requireFromString = require('require-from-string');

const m = requireFromString('module.exports = 1');

to call requireFromString with a string with the module’s code to require it.

As a result, m is 1.

Conclusion

To load a Node.js module from string in memory, we can use the require-from-string module.

Sometimes, we want to overwrite a file using fs in Node.js.

In this article, we’ll look at how to overwrite a file using fs in Node.js.

How to overwrite a file using fs in Node.js?

To overwrite a file using fs in Node.js, we can call writeFile or writeFileSync with the 'w' flag.

For instance, we write

fs.writeFileSync(path, content, {
  encoding: 'utf8',
  flag: 'w'
})

to call writeFileSync with the file path, file content, and the 'w' flag to write the file even if it already exists.

We can pass in the same arguments with writeFile to write the file asynchronously.

Conclusion

To overwrite a file using fs in Node.js, we can call writeFile or writeFileSync with the 'w' flag.

Sometimes, we want to write an image to a local server with Node.js.

In this article, we’ll look at how to write an image to a local server with Node.js.

How to write an image to a local server with Node.js?

To write an image to a local server with Node.js, we can use the fs.writeFile method.

For instance, we write

const http = require('http')
const fs = require('fs')

const options = {
  host: 'www.google.com',
  port: 80,
  path: '/images/logos/ps_logo2.png'
}

const request = http.get(options, (res) => {
  let imageData = ''
  res.setEncoding('binary')

  res.on('data', (chunk) => {
    imageData += chunk
  })

  res.on('end', () => {
    fs.writeFile('logo.png', imageData, 'binary', (err) => {
      if (err) {
        throw err
      }
      console.log('File saved.')
    })
  })
})

to call res.on with 'data' to listen for image data from the request we made with http.get.

We concatenate the chunks to imageData to combine the response data retrieved from the res stream.

And then we call res.on with 'end' to listen for the end event.

In the callback, we call writeFile with the imageData and 'binary' to write the file as binary data to logo.png.

The end event is emitted when the data is done reading.

Conclusion

To write an image to a local server with Node.js, we can use the fs.writeFile method.