How to Parse a Text File into an Array Line by Line in JavaScript

Learn how to efficiently parse a text file into an array line by line using JavaScript and the FileReader API. Simplify your file handling with this easy-to-follow guide!
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How to Parse a Text File into an Array Line by Line in JavaScript

Parsing a text file into an array line by line can seem tricky if you haven't worked with file handling in JavaScript before. Many developers encounter this issue and the confusion mostly arises in how to properly split the text into separate lines. In this post, we'll break down a straightforward solution to this problem.

The Problem

You have a text file that contains several names, each on a new line:

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The goal is to read this file and store each name as a separate element in an array, which should look like this:

[[See Video to Reveal this Text or Code Snippet]]

However, you may have noticed that your initial attempt did not yield the expected results. Let's look at the solution to ensure you achieve the desired output seamlessly.

The Solution

To parse a text file line by line in JavaScript, follow these steps:

1. Use the FileReader API

The FileReader API allows you to read the contents of files asynchronously, making it a useful tool for file parsing tasks.

2. Set Up Event Listener for File Input

You need to capture a file input from the user. Here’s how you can do that:

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3. Read the File

Implement an event listener to handle the file input change. Use the FileReader to read the file contents:

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4. Split the Content by Newline

The key to correctly parsing the text file lies in the split("\n") method. This allows you to split the content into an array wherever there is a newline character.

5. Output Verification

When you select a file, the console will display:

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This output indicates that each line from the file has been correctly parsed into an array!

Conclusion

Parsing a text file into an array line by line can easily be accomplished with the FileReader API. Remember to use split("\n") to ensure that the content is divided by new lines, instead of spaces. By following the steps outlined in this guide, you should have no problem implementing this functionality in your own projects.

Now, go ahead and start coding!