How to use the native Compression Streams API to compress and decompress strings in JavaScript

main.js

async function compressAndEncode(inputString) {
    const encoder = new TextEncoder();

    // Create a ReadableStream from the input string
    const inputReadableStream = new ReadableStream({
        start(controller) {
            controller.enqueue(encoder.encode(inputString));
            controller.close();
        }
    });

    // Compress the ReadableStream using the gzip algorithm
    const compressedStream = inputReadableStream.pipeThrough(new CompressionStream("gzip"));

    // Read the compressed data from the stream
    const reader = compressedStream.getReader();

    let compressedData = new Uint8Array();
    let result;

    while ((result = await reader.read())) {
        if (result.done) {
            // Encode the compressed data as a URI component
            const encodedData = encodeURIComponent(btoa(String.fromCharCode(...compressedData)));

            return encodedData;
        } else {
            compressedData = new Uint8Array([...compressedData, ...result.value]);
        }
    }
}

async function decompressAndDecode(encodedString) {
    const decoder = new TextDecoder();

    // Decode the URI-encoded compressed data
    const decodedData = atob(decodeURIComponent(encodedString));

    // Convert the decoded data to a Uint8Array
    const compressedData = new Uint8Array(decodedData.split("").map((c) => c.charCodeAt(0)));

    // Create a ReadableStream from the compressed data
    const compressedStream = new ReadableStream({
        start(controller) {
            controller.enqueue(compressedData);
            controller.close();
        }
    });

    // Decompress the ReadableStream using the gzip algorithm
    const decompressedStream = compressedStream.pipeThrough(new DecompressionStream("gzip"));

    // Read the decompressed data from the stream
    const reader = decompressedStream.getReader();

    let decompressedData = "";
    let result;

    while ((result = await reader.read())) {
        if (result.done) {
            return decompressedData;
        } else {
            decompressedData += decoder.decode(result.value);
        }
    }
}

// Usage
(async function() {
  let x = await compressAndEncode("Hello, World!");
  console.log(x);
  let y = await decompressAndDecode(x);
  console.log(y);
})();

Dear Alexis,
I would like to use this code in my App "MintApps" (https://codeberg.org/MintApps/client) which is under GPL3.
Would this be ok?
Best regards,
Thomas

@thk100: Yes, it would be totally fine, that's why I published it here!
Enjoy!

Thank you!