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Decompressing byte array compressed with LZ4 in JavaScript

I'm trying to decompress a byte array in JavaScript with lz4. I tried to implement the example in the npmjs page. I already have the data in compressed format, thus compressing it again leads to unwanted results.
I have tried:
var input = Buffer.from(this.bytes);
var output = Buffer.alloc( lz4.encodeBound(input.length) );
var uncompressed = Buffer.alloc(input.length);
var uncompressedSize = lz4.decodeBlock(output, uncompressed);
uncompressed = uncompressed.slice(0, uncompressedSize);
console.log( "uncompressed data", uncompressed);
Which leads to an array of 0's. I have confirmed that the data I pass (this.bytes) is a valid array of bytes. Ex: [f1,09,01,54,00,00,00,00,46,00,00,00,53,07,00,00,00,6f,66,66,73,65,74,58,4e,00,01,00,f1,35,2a,c0,53,08,00,00,00,69,74,65,6d,49,63,6f,6e,53,1f,00,00,00,57,65,61,70,6f,6e,45,6e,63,68,61,6e,74,6d,65,6e,74,5f,53,70,65,61,72,30,32,5f,4c,61,72,67,65,53,0b,00,00,00,53,63,72,65,65,6e,57,69,64,74,68,4e,49,00,55,00,9e,40,53,06,5f,00,01,73,00,f1,04,02,00,00,00,53,01,00]
I'd appreciate any help or suggestions.
Edit:
I have tried to directly decode the byte array:
console.log(LZ4.decode(this.bytes.join("")));
This leads to this error:
Uncaught (in promise) Error: Invalid magic number: 39303166 #0
emit_Error http://localhost:8080/javascripts/lz4.min.js:8
read_MagicNumber http://localhost:8080/javascripts/lz4.min.js:8
_main http://localhost:8080/javascripts/lz4.min.js:8
_transform http://localhost:8080/javascripts/lz4.min.js:8
_read http://localhost:8080/javascripts/lz4.min.js:8
_write http://localhost:8080/javascripts/lz4.min.js:8
b http://localhost:8080/javascripts/lz4.min.js:8
s http://localhost:8080/javascripts/lz4.min.js:8
write http://localhost:8080/javascripts/lz4.min.js:8
end http://localhost:8080/javascripts/lz4.min.js:8
LZ4_uncompress http://localhost:8080/javascripts/lz4.min.js:8
construct http://localhost:8080/javascripts/readSaveFile.js:194
Upon researching this issue, I came across this issue. I could not find the function lz4.createDecoderStream.prototype.uncompressBlock
I then tried an example from the node-lz4 github repo:
var compressed = Buffer.from(this.lua_state);
var uncompressedBlock = Buffer.alloc(compressed.length*10);
var n = LZ4.decodeBlock(compressed, uncompressedBlock);
uncompressedBlock = uncompressedBlock.slice(0,n);
console.log(uncompressedBlock);
Which returns, you guessed it, an array of 0's. I'm completely stuck right now and again appreciate any help.

The problem was that my input array was not an array of integers, so I just converted it into an UInt8Array with this function:
function convert_byte_array_to_int_array(array) {
let output_array = [];
array.forEach(byte => {
output_array.push(parseInt(byte, 16));
});
return output_array;
}
And used it in the package's example like this:
var input = convert_byte_array_to_int_array(this.bytes);
console.log(input);
var uncompressed = Buffer.alloc(input.length);
var uncompressedSize = LZ4.decodeBlock(input, uncompressed);
uncompressed = uncompressed.slice(0, uncompressedSize);
console.log( "uncompressed data", uncompressed );
Uncompressed data that was output to the console was the data I was looking for. Thank you for your help.

How to edit a byte at a given index in a "ArrayBuffer"

I can not found a way to change a value in an ArrayBuffer.
I am able to print the content of an ArrayBuffer by using a TextDecoder. When printing the buffer there is a string. I want to change one char on the string by editing one byte on the buffer. I was able to access one byte on the buffer by converting it to an Int8Array but I am not sure on how to converting it again to an ArrayBuffer after editing the byte
var enc = new TextDecoder("utf-8");
console.log('ArrayBuffer string content : ', enc.decode(data));
let view = new Int8Array(data);
view[56] = 48;
view[57] = 48;
// Convert view again to an ArrayBuffer
//console.log('ArrayBuffer string new content : ', enc.decode(data));

You can use the set method on your Int8Array directly :
var enc = new TextDecoder("utf-8");
console.log('ArrayBuffer string content : ', enc.decode(data));
let view = new Int8Array(data);
view.set([48], 56);
view.set([48], 57);

As stated in the top answer:
var enc = new TextDecoder("utf-8");
console.log('ArrayBuffer string content : ', enc.decode(data));
let view = new Int8Array(data);
view.set([48], 56);
view.set([48], 57);
It actually does change the byte value in the data variable.
I spend the last couple of hours trying to figure out how to do this, myself.
Then I finally understood that when you create the new Int8Array(), you're not creating a copy of the data - you're just creating a different type of pointer to it.
It's messy, it's confusing, but it works.
Cheers!

JSON.parse() - SyntaxError: Expected end of stream at char 2

In my project, I have written google spreadsheet script to decipher encrypted cell content using sjcl. But I failed.
function encryptCell() {
var masterKey = Browser.inputBox('Enter masterKey');
var spreadSheet = SpreadsheetApp.getActiveSpreadsheet();
var cell = spreadSheet.getActiveSheet().getActiveCell();
var input = cell.getValue();
var encJson = sjcl.encrypt(masterKey, input);
/*
{"iv":"4psT+LTIh/aT7WWv7Ye7qw==","v":1,"iter":1000,"ks":128,"ts":64,"mode":"ccm","adata":"","cipher":"aes","salt":"PjSOiia9TCM=","ct":"3hwmBbwQ7y/fsjk="}
*/
var encStr = JSON.stringify(encJson);
/*
"{\"iv\":\"4psT+LTIh/aT7WWv7Ye7qw==\",\"v\":1,\"iter\":1000,\"ks\":128,\"ts\":64,\"mode\":\"ccm\",\"adata\":\"\",\"cipher\":\"aes\",\"salt\":\"PjSOiia9TCM=\",\"ct\":\"3hwmBbwQ7y/fsjk=\"}"
*/
var encB64 = Utilities.base64Encode(encStr);
Browser.msgBox(encB64);
var rencStr = Utilities.base64Decode(encB64);
/*
34,123,92,34,105,118,92,34,58,92,34,52,112,115,84,43,76,84,73,104,47,97,84,55,87,87,118,55,89,101,55,113,119,61,61,92,34,44,92,34,118,92,34,58,49,44,92,34,105,116,101,114,92,34,58,49,48,48,48,44,92,34,107,115,92,34,58,49,50,56,44,92,34,116,115,92,34,58,54,52,44,92,34,109,111,100,101,92,34,58,92,34,99,99,109,92,34,44,92,34,97,100,97,116,97,92,34,58,92,34,92,34,44,92,34,99,105,112,104,101,114,92,34,58,92,34,97,101,115,92,34,44,92,34,115,97,108,116,92,34,58,92,34,80,106,83,79,105,105,97,57,84,67,77,61,92,34,44,92,34,99,116,92,34,58,92,34,51,104,119,109,66,98,119,81,55,121,47,102,115,106,107,61,92,34,125,34
*/
var rencJson = JSON.parse(rencStr);
var rinput = sjcl.decrypt(masterKey, rencJson);
Browser.msgBox(rinput);
}
Encryption is fine, which I can decrypt using this tool. Something is wrong with JSON.parse().

var rencStr = Utilities.base64Decode(encB64);
/*
34,123,92,34,105,118,92,34,58,92,34,52,112,115,84,43,76,84,73,104,47,97,84,55,87,87,118,55,89,101,55,113,119,61,61,92,34,44,92,34,118,92,34,58,49,44,92,34,105,116,101,114,92,34,58,49,48,48,48,44,92,34,107,115,92,34,58,49,50,56,44,92,34,116,115,92,34,58,54,52,44,92,34,109,111,100,101,92,34,58,92,34,99,99,109,92,34,44,92,34,97,100,97,116,97,92,34,58,92,34,92,34,44,92,34,99,105,112,104,101,114,92,34,58,92,34,97,101,115,92,34,44,92,34,115,97,108,116,92,34,58,92,34,80,106,83,79,105,105,97,57,84,67,77,61,92,34,44,92,34,99,116,92,34,58,92,34,51,104,119,109,66,98,119,81,55,121,47,102,115,106,107,61,92,34,125,34
*/
If you take a look, that's not JSON. did you possibly miss the JSON.stringify(); step for that one?
You can't parse it if it's not JSON.

When decoding with Utilities.base64Decode() you have one extra step to follow if you want to get a string back. If you look at the Google Scripts reference it says that base64Decode returns a byte array and not a string. Looking at your code, your decode returns
var rencStr = Utilities.base64Decode(encB64);
/*34,123,92,34,105,118,92,34,58,92,34,52,112,115,84,43,76,84,73,104,47,97,84...*/
which is a numeric representation of your string in Unicode. If you run your return value through Utilities.newBlob(rencStr).getDataAsString() as the reference recommends, you will have your JSON that you can parse back into your encrypted string.

JavaScript: reading 3 bytes Buffer as an integer

Let's say I have a hex data stream, which I want to divide into 3-bytes blocks which I need to read as an integer.
For example: given a hex string 01be638119704d4b9a I need to read the first three bytes 01be63 and read it as integer 114275. This is what I got:
var sample = '01be638119704d4b9a';
var buffer = new Buffer(sample, 'hex');
var bufferChunk = buffer.slice(0, 3);
var decimal = bufferChunk.readUInt32BE(0);
The readUInt32BE works perfectly for 4-bytes data, but here I obviously get:
RangeError: index out of range
at checkOffset (buffer.js:494:11)
at Buffer.readUInt32BE (buffer.js:568:5)
How do I read 3-bytes as integer correctly?

If you are using node.js v0.12+ or io.js, there is buffer.readUIntBE() which allows a variable number of bytes:
var decimal = buffer.readUIntBE(0, 3);
(Note that it's readUIntBE for Big Endian and readUIntLE for Little Endian).
Otherwise if you're on an older version of node, you will have to do it manually (check bounds first of course):
var decimal = (buffer[0] << 16) + (buffer[1] << 8) + buffer[2];

I'm using this, if someone knows something wrong with it, please advise;
const integer = parseInt(buffer.toString("hex"), 16)

you should convert three byte to four byte.
function three(var sample){
var buffer = new Buffer(sample, 'hex');
var buf = new Buffer(1);
buf[0] = 0x0;
return Buffer.concat([buf, buffer.slice(0, 3)]).readUInt32BE();
}
You can try this function.

How to convert float into byte array?

I want to convert a float value like 26,4 into a byte array. Something like: [51,51,-45,65]. Another example: 32,2 > [-51, -52, 0, 66].
I can do it in Arduino C++ and Python, but I don't see how to do it in JavaScript.
I have an input field in my HTML page where I want to write my float value and decode it before sending it to a Python script.
Is it possible?

Typed Arrays
First create a Float32Array which is a view on top of an actual byte-buffer (ArrayBuffer). We can allocate the buffer and view in a single operation:
var farr = new Float32Array(2); // two indexes each 4 bytes
Store the floating point numbers. These will be stored in IEEE-754 format:
farr[0] = 26.4;
farr[1] = 32.2;
Now we can add another view for the underlying buffer, this time signed 8-bit view:
var barr = new Int8Array(farr.buffer); // use the buffer of Float32Array view
console.log(barr);
// -> 51,51,-45,65,-51,-52,0,66
Live demo below
var farr = new Float32Array(2); // two indexes each 4 bytes
farr[0] = 26.4;
farr[1] = 32.2;
var barr = new Int8Array(farr.buffer); // use the buffer of Float32Array view
console.log(barr);
document.querySelector("div").innerHTML = barr[0]+","+barr[1]+","+barr[2]+","+barr[3]+","+barr[4]+","+barr[5]+","+barr[6]+","+barr[7];
<div></div>