We live in a strange world
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Replace C HTTP parser with JS HTTP parser by mscdex · Pull Request #1457 · nodejs/node
Background There had been brief mention during a TC meeting some time back about the possibility of having a js HTTP parser for io.js core. I was looking for a new and interesting project to work o...
The fact that this is not only possible but actually even slightly ... I can't believe I am going to say this ... reasonable is a little bit wild.
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Implementing something in JS for a JS framework? Say it isn't so!
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Implementing something in JS rather than C for speed
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Which to me says the C code was total garbage, not that JS is genuinely faster ;)
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Which to me says the C code was total garbage,
So is the js:
This parser uses regular expressions for most of the parsing.
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C code must've been utter garbage then. Though doing these things in C — especially nonblocking — is not easy.
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I think they're all just crazy js people, so it makes sense that they'd want to js all the things. For instance...
#Is it io.js or IO.js or iojs or IOjs or iOjS?
The official name is io.js, which should never be capitalized, especially not at the start of a sentence, unless it is being displayed in a location that is customarily all-caps (such as the title of man pages).
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Oy vey
.js
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Compare that to Node, who just say 'here's this thing we did', and get on with making the next version
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Goddamn I fucking hate Javascript.
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The fact that the C code wasn't as optimal as it could have been doesn't surprise me - it's that the JIT has gotten good enough that you need to be more-than-decent at C to get better performance than what V8 can get once it sees how you're using JavaScript. What's next, several typed / JIT versions of PHP?
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So is the js:
This parser uses regular expressions for most of the parsing.
You missed off a bit:
[ack that RE is wrong] However I wanted something that would be easy to get right
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Premature optimization:
#Various Performance Improvement Techniques
[...]
- Use val !== val instead of isNaN(val). NaN is the only value in JavaScript that does not equal itself or anything else.
jsperf
Just how frequently does this code check for NaN that (on this box) a difference of 15,777,846 vs 570,482,405 operations per second is going to make a noticeable difference?
Well the only instance of this I can find in the diff is this:
Replace C HTTP parser with JS HTTP parser by mscdex · Pull Request #1457 · nodejs/node
Background There had been brief mention during a TC meeting some time back about the possibility of having a js HTTP parser for io.js core. I was looking for a new and interesting project to work o...
``` if (val !== val || val > MAX_CHUNK_SIZE) return this._setError('Bad Content-Length'); ```
Well if they want premature optimization with obfuscation, why didn't they simply go for:
if (!(val <= MAX_CHUNK_SIZE)) return this._setError('Bad Content-Length');And that code seems to get run only when it's going through the header. I doubt a profiler has been anywhere near this code.
- Use val !== val instead of isNaN(val). NaN is the only value in JavaScript that does not equal itself or anything else.
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You missed off a bit:
[ack that RE is wrong] However I wanted something that would be easy to get right
And that bit should get the prefix, So is the author.
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> - Use val !== val instead of isNaN(val). NaN is the only value in JavaScript that does not equal itself or anything else.
That is another amazing JS feature. Like this:typeof(null)
"object"
null instanceof Object
falseor JSON.stringify(Infinity). To think that is the standard that implementers have to uphold. Brrrrr.
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That is another amazing JS feature
BZZT!
NaN != NaNis guaranteed by IEEE 754 -- it's the same way in C++, Python, JS, and basically every other language on a modern system. (isnanwasn't a thing in C until oh, C99...)
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typeof(null)
"object"
null instanceof Object
falsemakes perfect sense if you understand that setting a variable to null simply creates a special object reference that doesn't point to anything, almost completely analogous to a 0 pointer in C.
The typeof operator sees that the variable holds an object reference, as opposed to a primitive value type like number or string or boolean or undefined; the instanceof operator tries to follow the prototype chain on the referenced object to see if it leads back to the global Object object, but can't do that because the object reference doesn't actually refer to anything at all.
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makes perfect sense if you understand
that setting a variable to null simply creates a special object referencethe weird implementation details<FTFY
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To be fair, null is a special value for pointer types in a lot of languages, not just js.
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