dekkai

dekkai

Modern and fast, really fast, CSV parser for the browser and node.js

WARNING: This is pre-release code, although stable, some features have not been implemented yet.

Installation

yarn add dekkai

or

npm install dekkai

Usage

Loading a file

In the browser:

import {dekkai} from 'dekkai';

async function main() {
    const fileInput = document.createElement('input');
    fileInput.setAttribute('type', 'file');
    fileInput.setAttribute('name', 'dataFile');
    document.body.appendChild(fileInput);
    
    fileInput.addEventListener('change', async e => {
        e.preventDefault();
        await dekkai.init(/* number of threads, blank for auto-detect */);
        
        const table = await dekkai.loadLocalFile(fileInput.files[0]);
    });
}

main();

In Node.js

const dekkai = require('dekkai/dist/umd/dekkai');
const path = require('path');
const fs = require('fs');

function open(file) {
    return new Promise((resolve, reject) => {
        fs.open(path.resolve(file), (err ,fd) => {
            if (err) {
                reject(err);
            } else {
                resolve(fd);
            }
        });
    });
}

async function main() {
    await dekkai.init(/* number of threads, blank for auto-detect */);
    const file = await open(path.resolve(__dirname, '../Airports2.csv'));
    const table = await dekkai.loadLocalFile(file);
}

main();

Accessing the data

/* access the data through the table methods */
table.setColumnType('Fly_date', 'string'); // overwrite the specified column's detected type
table.setColumnType(13, 'int'); // can be done by column index

/* iterate through all the rows */
await table.forEach(row => {
    console.log(row.valueByName('Origin_city')); // get a value by column name
    console.log(row.valueByNameTyped('Passengers')); // parse the value as its type
    console.log(row.valueByIndex(0)); // get a value by column index
    console.log(row.valueByNameTyped(6)); // parse the value as its type
});

/* get arbitrary row numbers */
for (let i = 100; i < 200 && i < table.rowCount; ++i) {
    const row = await table.getRow(i);
    let str = '';
    /* iterate over all the values in the row */
    row.forEach(value => {
        str += value + '\t';
    });
    console.log(str);
}

Teardown

/* terminate dekkai */
dekkai.terminate();

Example

• Checkout this repo
• Install yarn if needed.
• On the command line navigate to the repo's folder
• Run yarn install
• Run yarn start and wait for project to build
• In your browser, navigate to localhost:8090
• Load a CSV huge CSV file!

Benchmark

CPU: 6 cores, 2.6 GHz, Core i7 (I7-8850H)
File: Airports2.csv, 15 columns, 3606803 rows, 509MB

Language	Library	Typed	Single-thread	Multi-thread(6)
JS (Node)	dekkai	Yes	5629ms	1088ms
JS (Web)	dekkai	Yes	5311ms	1156ms
C++11	fast-cpp-csv-parser	Yes	1797ms	N/A
Go	encoding/csv	N/A	2135ms	N/A
Go	weberc2/fastcsv	N/A	3075ms	N/A
C++11	AriaFallah/csv-parser	N/A	4011ms	N/A
JS (Web)	Papa Parse 4	No	11913ms	N/A
JS (Web)	Papa Parse 4	Yes	19508ms	N/A
JS (Node)	fast-csv	N/A	35789ms	N/A