Byte array to Hex string conversion in javascript

javascript arrays bitcoin data-conversion
Actung picture Actung · Dec 16, 2015 · Viewed 49.6k times · Source

I have a byte array of the form [4,-101,122,-41,-30,23,-28,3,..] which I want to convert in the form 6d69f597b217fa333246c2c8 I'm using below function

function toHexString(bytes) {
  return bytes.map(function(byte) {
    return (byte & 0xFF).toString(16)
  }).join('')
}

which is giving me a string of the same form but I suspect that it's not an efficient conversion because the hex string is bit shorter than expected. I think translating should get "0a10a6dc". Please tell me if I'm wrong or is this a right conversion but maybe I'm not using the right byte array

byte array 4,-127,45,126,58,-104,41,-27,-43,27,-35,100,-50,-77,93,-16,96,105,-101,-63,48,-105,49,-67,110,111,26,84,67,-89,-7,-50,10,-12,56,47,-49,-42,-11,-8,-96,-117,-78,97,-105,9,-62,-44,-97,-73,113,96,23,112,-14,-62,103,-104,90,-14,117,78,31,-116,-7

Corresponding conversion 4812d7e3a9829e5d51bdd64ceb35df060699bc1309731bd6e6f1a5443a7f9ceaf4382fcfd6f5f8a08bb261979c2d49fb771601770f2c267985af2754e1f8cf9

Answer

Bergi picture Bergi · Dec 16, 2015

You are missing the padding in the hex conversion. You'll want to use

function toHexString(byteArray) {
  return Array.from(byteArray, function(byte) {
    return ('0' + (byte & 0xFF).toString(16)).slice(-2);
  }).join('')
}

so that each byte transforms to exactly two hex digits. Your expected output would be 04812d7e3a9829e5d51bdd64ceb35df060699bc1309731bd6e6f1a5443a7f9ce0af4382fcfd6f5f8a08bb2619709c2d49fb771601770f2c267985af2754e1f8cf9

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