[deno]

Better than node.js

    import * as csv from 'csv-parse';
    import * as fs from 'fs';
    
    type Line = [string,string,string,string,string,string];
    
    const parser = new csv.Parser({});
    
    parser.on('data', (line: Line) => { 
    if (line[0] === '42') {
            console.dir(line);
        } 
    });
    
    fs.createReadStream('mock_data.csv').pipe(parser);
    
    $ /usr/bin/time node parse_csv.js
    43.61user 0.85system 0:45.61elapsed 97%CPU (0avgtext+0avgdata 60076maxresident)k
    
    $ node --version
    v6.4.0

Edit: Using fast-csv

    24.28user 0.20system 0:24.58elapsed 99%CPU (0avgtext+0avgdata 91780maxresident)k

[elmigranto]

Probably has to do with using `try/catch` whis is not omptimized by V8. Different parser is 10 times faster on my machine.

https://www.npmjs.com/package/csv-parser

Edit: `fast-csv` seems to be using a lot of `RegExp`s on each iteration which can't be that fast compared to csv-parser which seems to simply go over each symbol (state machine?).

[deno]

    4.95user 0.19system 0:05.22elapsed 98%CPU (0avgtext+0avgdata 29704maxresident)k

A lot better but that’s still 5× slower than Python.

[masklinn]

csv-parse is hardly the only CSV parser for node, and it is by far the slowest: https://github.com/phihag/csv-speedtest (csv2json depends on csv-parse, so it's unsurprising that it's even slower)

[deno]

I chose the most popular one on npm because Go and Python are using stdlib.

[elmigranto]

But you still wrote "faster than node.js" and not "faster that most popular npm module" (which aren't always of a great quality or performance-oriented).

[deno]

Yup[1]. Sorry!

[1] https://meta.wikimedia.org/wiki/Cunningham%27s_Law

[deno]

The fastest streaming example on that list (csv-parser) is still 5× slower than Python.

[masklinn]

Which I'd assume has to do with the overhead of dispatching a ton of asynchronous events for relatively little parsed data rather than the intrinsic speed of node, the fastest synchronous parsers of the list are about on-par with Python.

[weberc2]

You don't need to drop quote handling in order to stream, but handling quotes is a pain.