I have this GZIPed string: H4sIAAAAAAAA//NIzcnJVyguSUzOzi9LLUrLyS/XUSjJSMzLLlZIyy9SSMwpT6wsVshIzSnIzEtXBACs78K6LwAAAA==
I created that with this website: http://www.txtwizard.net/compression
I have tried using pako to ungzip it.
import { ungzip } from 'pako';
const textEncoder = new TextEncoder();
const gzipedData = textEncoder.encode("H4sIAAAAAAAA//NIzcnJVyguSUzOzi9LLUrLyS/XUSjJSMzLLlZIyy9SSMwpT6wsVshIzSnIzEtXBACs78K6LwAAAA==");
console.log('gzipeddata', gzipedData);
const ungzipedData = ungzip(gzipedData);
console.log('ungziped data', ungzipedData);
The issue is that Pako throws the error: incorrect header check
What am I missing here?
This string is base64-encoded.
You first need to decode it to a buffer:
const gzippedString = 'H4sIAAAAAAAA//NIzcnJVyguSUzOzi9LLUrLyS/XUSjJSMzLLlZIyy9SSMwpT6wsVshIzSnIzEtXBACs78K6LwAAAA==';
const gzippedBuffer = new Buffer(gzippedString, 'base64');
Then you can un(g)zip it:
const unzippedBuffer = ungzip(gzippedBuffer);
The result on ungzip is a Unit8Array. If you want to convert it back to a string you'll need to decode it again:
const unzippedString = new TextDecoder('utf8').decode(unzipped);
The "H4sIAAAAAAAA//NIzcnJVyguSUzOzi9LLUrLyS/XUSjJSMzLLlZIyy9SSMwpT6wsVshIzSnIzEtXBACs78K6LwAAAA==" is a base64 encoded string, you first need to decode that into a buffer.
textEncoder.encode just encodes that base64 encoded string into a byte stream.
How to do that depend on whether you are in a browser or on nodejs.
To convert the unzipped data to a string you further have use new TextDecoder().decode()
For node you will use Buffer.from(string, 'base64') to decode the base64 encoded string:
import { ungzip } from 'pako';
// decode the base64 encoded data
const gzipedData = Buffer.from("H4sIAAAAAAAA//NIzcnJVyguSUzOzi9LLUrLyS/XUSjJSMzLLlZIyy9SSMwpT6wsVshIzSnIzEtXBACs78K6LwAAAA==", "base64");
console.log('gzipeddata', gzipedData);
const ungzipedData = ungzip(gzipedData);
console.log('ungziped data', new TextDecoder().decode(ungzipedData));
In the browser, you have to use atob, and you need to convert the decoded data to an Uint8Array using e.g. Uint8Array.from.
The conversion I used was taken from Convert base64 string to ArrayBuffer, you might need to verify if that really works in all cases.
// decode the base64 encoded data
const gezipedData = atob("H4sIAAAAAAAA//NIzcnJVyguSUzOzi9LLUrLyS/XUSjJSMzLLlZIyy9SSMwpT6wsVshIzSnIzEtXBACs78K6LwAAAA==")
const gzipedDataArray = Uint8Array.from(gezipedData, c => c.charCodeAt(0))
console.log('gzipeddata', gzipedDataArray);
const ungzipedData = pako.ungzip(gzipedDataArray);
console.log('ungziped data', new TextDecoder().decode(ungzipedData));<script src="https://cdnjs.cloudflare.com/ajax/libs/pako/2.0.4/pako.min.js"></script>