node.js - Javascript hex string fromCharCode - Stack Overflow

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Hex string:

var str = [0x6A, 0xE8, 0x05, 0x01, 0x00, 0x01, 0xD9, 0xDC, 0x0A, 0x09];
byte = '';
for (var i=0; i < str.length; i++) {
    byte += String.fromCharCode( parseInt(str[i], 16).toString(16) );
}

But receiver show:

6A C3A8 05 01 00 01 C399 C39C 0A 09

Any idea how to keep it 2 bytes? Or maybe my code wrong, esp. for nodejs?

*Updated the script. I'm kinda new with nodejs and I like to see what non-blocking events nodejs' offer because in "busy" day I have some missing data. Got the script working for python using binascii.(un)hexlify and PHP mbstring (un)pack (for web view).

Expecting:

6A E8 05 01 00 01 D9 DC 0A 09

Hex string:

var str = [0x6A, 0xE8, 0x05, 0x01, 0x00, 0x01, 0xD9, 0xDC, 0x0A, 0x09];
byte = '';
for (var i=0; i < str.length; i++) {
    byte += String.fromCharCode( parseInt(str[i], 16).toString(16) );
}

But receiver show:

6A C3A8 05 01 00 01 C399 C39C 0A 09

Any idea how to keep it 2 bytes? Or maybe my code wrong, esp. for nodejs?

*Updated the script. I'm kinda new with nodejs and I like to see what non-blocking events nodejs' offer because in "busy" day I have some missing data. Got the script working for python using binascii.(un)hexlify and PHP mbstring (un)pack (for web view).

Expecting:

6A E8 05 01 00 01 D9 DC 0A 09

• javascript
• node.js
• hex

Share Improve this question Follow edited Dec 20, 2012 at 5:25 lontongcorp asked Dec 18, 2012 at 21:43 lontongcorplontongcorp 13811 silver badge88 bronze badges 3

• Why do you need: "String.fromCharCode" If you're already using: ".toString(16)" then you've already got a String . – Foggzie Commented Dec 18, 2012 at 22:00
• 1) Try typing 0x6a in node interpreter and see what happens, note how it differs from "0x6a". 2) Argument for String.fromCharCode is super strange. 3) Also, don't use for in with arrays. – Aleksei Zabrodskii Commented Dec 18, 2012 at 22:50
• This is for munication purpose. I need to translate the hexstring ining message, create the response message, send the response message back as hexstring too. So I need String.fromCharCode and quite confuse why it is called super strange. Thanks for the tips for {for in} ;) – lontongcorp Commented Dec 20, 2012 at 5:32

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2 Answers 2

Sorted by: Reset to default 5

Your code seems to be working for me if I decode it again. Careful though with for() loops over objects in Javacript. That also iterates over the properties of an object.

var str = [0x6A, 0xE8, 0x05, 0x01, 0x00, 0x01, 0xD9, 0xDC, 0x0A, 0x09];
byte = '';
for (var i=0; i < str.length; i++) {
    byte += String.fromCharCode( parseInt(str[i], 16).toString(16) );
}

var hexarrayout = [];
for (var i=0; i<byte.length; i++) {
    hexarrayout.push(byte.charCodeAt(i).toString(16));
}

alert(hexarrayout);

​ Example on http://jsfiddle/ycG4n/

Your problem looks very much like a utf8<=>iso-.../ascii/etc conversion problem when sending to your receiver, where some of your 1byte string chars are converted into 2byte chars. Due to the partial backwards patibility of UTF-8, some of your hex values would be kept 1byte.

Even though you're writing 0x6A in your code, JavaScript automatically understands it as its value, 106. It is already a number, so parseInt() won't do anything to it and can be removed.

You might just want to do this:

var str = [0x6A,0xE8...];
var byte = String.fromCharCode.apply(null,str);

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