Bun stdin one line only

2 min read 04-10-2024

Harnessing Bun's Power: Reading One Line from Standard Input

Bun, the blazing fast JavaScript runtime, empowers developers with its versatility. One common task is reading input from the standard input stream (stdin). But what if you only need to process a single line of data? Let's explore how to achieve this efficiently using Bun.

The Challenge: Reading a Single Line

Imagine you have a script that expects a user to input a single line of text. You might encounter scenarios like:

Processing command-line arguments: Your script might analyze a file path or a specific configuration setting.
Simple data interaction: You need to take user input, perform a calculation, and output the result.

Directly reading from stdin using process.stdin in Node.js can lead to complications when dealing with line-by-line input.

Bun to the Rescue: A Streamlined Approach

Here's a simple Bun script that elegantly handles single-line input:

import { stdin } from "process";

const line = await stdin.read().then(data => data.toString().trim());
console.log(`You entered: ${line}`);

Let's break down the code:

Import stdin: We begin by importing the stdin object from the process module.
Asynchronous Read: The stdin.read() method is used to read data from the standard input stream asynchronously. It returns a promise that resolves with a buffer containing the input.
Conversion and Trimming: The promise is then chained with a .then() callback to convert the buffer into a string using data.toString() and trim any leading or trailing whitespace with .trim().
Output: Finally, the trimmed input is logged to the console.

The Advantages of Bun

Concise: Bun's syntax is clean and straightforward, making it easier to write and understand.
Asynchronous Efficiency: The use of promises ensures non-blocking I/O, preventing the script from getting stuck waiting for input.
Performance: Bun's performance is consistently impressive, making it an excellent choice for handling even large amounts of data.

Beyond Single Lines: Expanding the Possibilities

This approach can be adapted to handle more complex scenarios:

Multiple Line Input: You can use a loop to read multiple lines until a specific condition is met (e.g., an empty line, a specific keyword).
Data Processing: After reading a single line, you can perform any desired data manipulation, calculations, or transformations.
Integration with Other Tools: This technique can be incorporated into more extensive scripts that interact with other utilities, like file systems or network services.

Conclusion

Reading single lines from stdin is a fundamental task in various programming scenarios. Bun's elegant and efficient approach empowers developers to handle this operation with ease. Whether you're building command-line tools, data processors, or interactive scripts, Bun provides a streamlined and powerful solution.

Remember to explore the Bun documentation and community resources for more in-depth examples and advanced techniques.