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Incorrect documentation or bug in Node #9165
Description
Per this documentation: https://nodejs.org/dist/latest-v4.x/docs/api/buffer.html#buffer_class_method_buffer_from_array
Buffer.from(array) was added in v3.0. However, this example (taken from docs) fails in Node v4.2.3 and Node v4.4.4
const buf = Buffer.from([0x62,0x75,0x66,0x66,0x65,0x72]);
// creates a new Buffer containing ASCII bytes
// ['b','u','f','f','e','r'] <-- fails in Node < v4.5.0
// error
TypeError: this is not a typed array.
at Function.from (native)
at repl:1:20
at REPLServer.defaultEval (repl.js:262:27)
at bound (domain.js:287:14)
at REPLServer.runBound [as eval] (domain.js:300:12)
at REPLServer.<anonymous> (repl.js:431:12)
at emitOne (events.js:82:20)
at REPLServer.emit (events.js:169:7)
at REPLServer.Interface._onLine (readline.js:211:10)
at REPLServer.Interface._line (readline.js:550:8)
Now as per latest docs: https://nodejs.org/api/buffer.html#buffer_class_method_buffer_from_array, our friend seems to have been "added in v5.10.0"
And rightfully so, fails in v5.0.0
λ rpm-extract → λ git master* → node -v
v5.0.0
λ rpm-extract → λ git master* → node
> console.log(Buffer.from([0x62,0x75,0x66,0x66,0x65,0x72]))
TypeError: this is not a typed array.
at Function.from (native)
at repl:1:20
So, my question is:
- Documentation is inconsistent and misleading.
- I want to support node v4 and v6. But this intermittent behavior will cause unwanted issues for consumers who are on > 4.0 and < 5.10.0 . What's the best way to handle this?
All the tests were done using nvm on a 64 bit OSX El Capitan.
Activity
addaleax commentedon Oct 18, 2016
So, one thing: The docs for v4.x should say it was introduced in
v4.5.0; before that,Buffer.fromis just inherited fromUint8Array.from, which has only thefrom(array)That is because
Uint8Array.fromactually checks whether it was called asUint8Array.from, notBuffer.from.Yeah, that should be easy to fix.
If you want/need to support versions below < 4.5 and < 5.10.0, you’ll likely have to stick with
new Buffer()for now; otherwise,Buffer.from()should be okay.mrchief commentedon Oct 18, 2016
Sounds good!
Out of curiosity,
Buffer.from(Uint8Array.from([0x62,0x75,0x66,0x66,0x65,0x72]))should work across the board then? Will that be a performance sucker?addaleax commentedon Oct 18, 2016
Not for Node < 4.5.0, due to the way in which V8 implements
Uint8Array.from. :/mrchief commentedon Oct 18, 2016
Yeah. All of these fail (but different node versions complain differently)
So 2 things remain:
new Bufferis deprecated in 6. I care for node v4 LTS and Node 6 only so thinking of this as a stop gap (until v4 support ends)addaleax commentedon Oct 18, 2016
Are you referring to the fact that v5.10.0 seems higher than v4.5.0, so it should incorporate features that are in all v4.x versions? Chronologically, v4.5.0 was released 5 months later than v5.10.0, and v4.x is still actively maintained. Occasionally, important new features like
Buffer.fromare backported there.Fwiw, there are a few polyfills available on npm. Also, you can just use
new Buffer(arr)(but be sure to read the part of the Buffer docs that explain why it’s deprecated) – it doesn’t come with a runtime warning so far, and it’s quite possible thatnew Buffer()will never truly be broken.mrchief commentedon Oct 18, 2016
I was referring to v5.0 (in my OP) but I guess this answers that as well.
For my current use case, I need
new Buffer(arr). That seems pretty safe since I couldn't spot any warning related to that.addaleax commentedon Oct 18, 2016
No, as long as you know that the input type will always be the same, everything’s fine with using the old API – It’s when you accept input that could be controlled by somebody else (like from the browser) where things get potentially unsafe.
doc: correct metadata of `Buffer.from`
doc: correct metadata of `Buffer.from`
targos commentedon Jan 8, 2017
Fixed in #9167