svelte/sites/svelte-5-preview/src/routes/gzip.js

/** @param {string} input */
export async function compress_and_encode_text(input) {
	const reader = new Blob([input]).stream().pipeThrough(new CompressionStream('gzip')).getReader();
	let buffer = '';
	for (;;) {
		const { done, value } = await reader.read();
		if (done) {
			reader.releaseLock();
			return btoa(buffer).replaceAll('+', '-').replaceAll('/', '_');
		} else {
			for (let i = 0; i < value.length; i++) {
				// decoding as utf-8 will make btoa reject the string
				buffer += String.fromCharCode(value[i]);
			}
		}
	}
}

/** @param {string} input */
export async function decode_and_decompress_text(input) {
	const decoded = atob(input.replaceAll('-', '+').replaceAll('_', '/'));
	// putting it directly into the blob gives a corrupted file
	const u8 = new Uint8Array(decoded.length);
	for (let i = 0; i < decoded.length; i++) {
		u8[i] = decoded.charCodeAt(i);
	}
	const stream = new Blob([u8]).stream().pipeThrough(new DecompressionStream('gzip'));
	return new Response(stream).text();
}