Reading Local Text File Into A Javascript Array Duplicate

When it comes to working with text files in JavaScript, there's a handy task that often comes up: reading the contents of a local text file into an array. This process allows you to access and manipulate the data within the text file easily.

To begin, you'll need to decide how you want to read the text file. One common approach is to use the File System Access API, which provides secure access to the user's local file system. However, for this article, we'll focus on a simpler method that involves using the FileReader API.

The FileReader API in JavaScript allows you to read the contents of a file asynchronously. To read a local text file using this API, you first need to create an input element in your HTML file where users can select the file they want to read. This input element will trigger a change event, allowing you to handle the file selection.

Next, you'll need to add an event listener to handle the file selection and read the contents of the selected file. Here's a basic example of how you can achieve this:

const fileInput = document.getElementById('fileInput');

fileInput.addEventListener('change', (event) => {
  const file = event.target.files[0];
  const reader = new FileReader();

  reader.onload = () => {
    const contents = reader.result;
    const dataArray = contents.split('n');
    console.log(dataArray);
  }

  reader.readAsText(file);
});

In this code snippet, we first retrieve the selected file using `event.target.files[0]`. We then create a new instance of `FileReader` and set up an `onload` event handler. When the file is successfully read, the `onload` function splits the file contents by newline characters ('n') and stores them in an array named `dataArray`. You can then perform further operations on this array as needed.

It's important to note that reading local files using JavaScript is subject to browser security restrictions. Most modern browsers will only allow file access in certain scenarios, such as when the file input element is manually triggered by the user.

By following these steps and understanding how to work with the FileReader API, you can easily read the contents of a local text file into a JavaScript array. This knowledge will be particularly helpful when dealing with tasks that involve processing data stored in text files. Remember to always handle file reading operations asynchronously and consider the security implications when working with local files in a web environment.