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Apply Gzip Compression Using the Compression Streams API in JavaScript

Last updated: December 12, 2024

Introduction to Gzip Compression

Gzip compression is a popular method of reducing the size of data transferred over the web. Implementing Gzip on a server is one effective way to decrease bandwidth usage and speed up loading times for users. However, with modern APIs, we can also perform compression directly within web applications using JavaScript, making it feasible to manage larger datasets client-side without first server-side decompression.

The Compression Streams API

The Compression Streams API in JavaScript allows developers to compress or decompress streams of data right within the browser. The API supports both Gzip and Deflate compression formats. This is particularly useful for web applications that handle large amounts of text or binary data since it enables client-side compression before sending data over the network.

Before diving into the implementation, ensure that your development environment is set up to run modern JavaScript and you are using an up-to-date browser that supports the Compression Streams API.

Implementing Gzip Compression

Below, we will look at a basic example of how to use the Compression Streams API to compress data using Gzip.

// Function to compress data using Gzip
async function compressData(data) {
    // Create a new Gzip stream
    const compressionStream = new CompressionStream('gzip');

    // Use a TextEncoder to convert a string to a Uint8Array
    const uint8Data = new TextEncoder().encode(data);

    // Create a new ReadableStream from the source data
    const readableStream = new ReadableStream({
        start(controller) {
            controller.enqueue(uint8Data);
            controller.close();
        }
    });

    // Pipe the ReadableStream through the compressionStream to get a compressed stream
    const compressedStream = readableStream.pipeThrough(compressionStream);

    // Collect the compressed chunks back into a single blob
    const chunks = [];
    const reader = compressedStream.getReader();
    while (true) {
        const { done, value } = await reader.read();
        if (done) break;
        chunks.push(value);
    }

    return new Blob(chunks);
}

This function showcases a simple way to compress a string of data. A real-world scenario might involve sending this compressed data to a server or storing it locally for later retrieval and decompression.

Decompressing Gzip Data

Decompression of Gzip data follows a similar logic. The only difference lies in the use of a DecompressionStream instead of a CompressionStream. Here's how you can decompress Gzip-compressed data:

// Function to decompress data using Gzip
async function decompressData(blob) {
    // Create a new DecompressionStream
    const decompressionStream = new DecompressionStream('gzip');

    // Create a response from the blob
    const response = new Response(blob);

    // Get the ReadableStream from the response
    const readableStream = response.body;

    // Pipe the ReadableStream through the decompressionStream
    const decompressedStream = readableStream.pipeThrough(decompressionStream);

    // Convert the decompressed stream back into a string
    const reader = new Response(decompressedStream).body.getReader();

    // UTF-8 decoder to decode stream bytes into text
    const decoder = new TextDecoder('utf-8');
    let decompressedData = '';

    while (true) {
        const { done, value } = await reader.read();
        if (done) break;
        decompressedData += decoder.decode(value, { stream: true });
    }

    return decompressedData;
}

Both compressing and decompressing streams need appropriate error handling for robustness in production environments.

Conclusion

The Compression Streams API provides a powerful and flexible way to manage data compression and decompression directly in your JavaScript applications. By understanding how to implement this, developers can optimize data transfer, improving application performance and user experience. As browsers continue to adopt modern web APIs, leveraging such utilities can present significant advantages.

Next Article: Reduce Payload Size with Compression Streams in JavaScript

Previous Article: Optimize Data Transfer with Compression Streams in JavaScript

Series: Web APIs – JavaScript Tutorials

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