Gzip a string in javascript using pako.js - Stack Overflow

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I was able to depress a string in JavaScript using pako.js

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// Get some base64 encoded binary data from the server. Imagine we got this:
var b64Data     = 'H4sIAAAAAAAAAwXB2w0AEBAEwFbWl2Y0IW4jQmziPNo3k6TuGK0Tj/ESVRs6yzkuHRnGIqPB92qzhg8yp62UMAAAAA==';

// Decode base64 (convert ascii to binary)
var strData     = atob(b64Data);

// Convert binary string to character-number array
var charData    = strData.split('').map(function(x){return x.charCodeAt(0);});

// Turn number array into byte-array
var binData     = new Uint8Array(charData);

// Pako magic
var data        = pako.inflate(binData);

// Convert gunzipped byteArray back to ascii string:
var strData     = String.fromCharCode.apply(null, new Uint16Array(data));

// Output to console
console.log(strData);

I want a method to press string and output can be depressed by above code using pako and gzip.

How can I do that?

I was able to depress a string in JavaScript using pako.js

http://jsfiddle/9yH7M/1/

// Get some base64 encoded binary data from the server. Imagine we got this:
var b64Data     = 'H4sIAAAAAAAAAwXB2w0AEBAEwFbWl2Y0IW4jQmziPNo3k6TuGK0Tj/ESVRs6yzkuHRnGIqPB92qzhg8yp62UMAAAAA==';

// Decode base64 (convert ascii to binary)
var strData     = atob(b64Data);

// Convert binary string to character-number array
var charData    = strData.split('').map(function(x){return x.charCodeAt(0);});

// Turn number array into byte-array
var binData     = new Uint8Array(charData);

// Pako magic
var data        = pako.inflate(binData);

// Convert gunzipped byteArray back to ascii string:
var strData     = String.fromCharCode.apply(null, new Uint16Array(data));

// Output to console
console.log(strData);

I want a method to press string and output can be depressed by above code using pako and gzip.

How can I do that?

• javascript
• gzip
• pression
• pako

Share Improve this question Follow edited Jun 4, 2018 at 13:52 krlzlx 5,8221414 gold badges4949 silver badges5959 bronze badges asked Jun 4, 2018 at 13:16 sireeshasireesha 11911 gold badge11 silver badge66 bronze badges 3

• What's going wrong when you simply do what's written in the docs? Note that pako has options to press/depress to/from string, so your typed array is not necessary. – ASDFGerte Commented Jun 4, 2018 at 13:20
• 1 @ASDFGerte I am doing var str ="Hello world"; var test = pako.gzip(new Uint8Array(str), {to: 'string'}); alert(btoa(test)); I get same output " H4sIAAAAAAAAAwMAAAAAAAAAAAA= " for any string and also not able to get back the original string after depressing the output. Where am I going wrong? – sireesha Commented Jun 5, 2018 at 5:32
• The way you construct your Uint8Array is not working (always empty) - debugging your test for a short moment would quickly tell you that. You could fix that, but way easier is noticing that in gzip(data[, options]), data has a described type of "Uint8Array | Array | String", which means you can just do let test = pako.gzip(str, {to: 'string'});. Reverting the process is as simple as pako.ungzip(test, { to: 'string' });. – ASDFGerte Commented Jun 5, 2018 at 8:06

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2 Answers 2

Sorted by: Reset to default 6

Compression:

let pressed_str = pako.gzip(str, {to: 'string'});

Depression:

let original_str = pako.ungzip(pressed_str, { to: 'string' });

There is a duplicate question, so I'm sharing my answer here.

https://stackoverflow./a/75934779/7295761

{to: 'string'} simply doesn't work for latest pako.js

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