How convert a string to type Uint8Array in nodejs

Question

How do I convert a string to a Uint8Array in node?
I don't normally develop in Javascript and this is driving me nuts. They offer a conversion Uint8Array.toString() but not the other way around. Does anyone know of an easy way for me to do this without creating my own parser?
I have seen some other answers to this, but they don't seem to address this specific class type

Similar answer for UTF-8 string to UInt8Array stackoverflow.com/questions/18729405/… — nezort11
– nezort11, Commented May 8, 2024 at 11:47

Patrick Roberts · Accepted Answer · 2020-07-10 17:42:12Z

34

You can use Buffer.from(string[, encoding]). The Buffer class has implemented the Uint8Array interface in Node since v4.x. You can also optionally specify an encoding with which to do string processing in both directions, i.e. buffer.toString([encoding]).

edited Jul 10, 2020 at 17:42

answered Jul 10, 2020 at 17:39

Patrick Roberts

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Siyavash Hamdi · Accepted Answer · 2022-09-13 09:24:07Z

24

Why not simply using:

const resEncodedMessage = new TextEncoder().encode(message)

answered Sep 13, 2022 at 9:24

Siyavash Hamdi

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Octo Poulos · Accepted Answer · 2021-06-22 21:31:43Z

15

Uint8Array.from(text.split('').map(letter => letter.charCodeAt(0)));

or (appears about 18% faster):

Uint8Array.from(Array.from(text).map(letter => letter.charCodeAt(0)));

Note: These only work for ASCII, so all the letters are modulo 256, so if you try with Russian text, it won't work.

edited Jun 22, 2021 at 21:31

answered Jun 22, 2021 at 21:13

Octo Poulos

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5 Comments

Heretic Monkey Over a year ago

Answers with explanation of code generally do better than code dumps which leave it to others to interpret. Also, text.split('') doesn't work well for Unicode strings; see How to get character array from a string?

Octo Poulos Over a year ago

Well you replied just as I was editing the answer. Indeed it's not good for unicode but this method is very simple and fast and might be exactly what he's looking for.

Hashbrown Over a year ago

I'd probably just delete that first code snippet as Array.from does respect logical character iteration, and your only issue is charCodeAt, which I would swap to .codePointAt(0) (which can return up to a 32bit number); here you can throw an exception, if you really do expect the codepoints to always be below 512.

Hashbrown Over a year ago

Btw, this will always work: Uint8Array.from(encodeURI(text).split(/%|(?<!%.?)/).map((x) => ((x[1]) ? parseInt(x, 16) : x.charCodeAt(x))))

WORMSS May 17 at 21:14

I was just wondering why did you need the array? Cannot you just go straight to Uint8Array.from(text, letter => letter.charCodeAt(0))

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