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January 5, 2019 11:44
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2 approaches to reading text files with node.js
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| const fs = require('fs'); | |
| const util = require('util'); | |
| const readFile = util.promisify(fs.readFile); | |
| const readdir = util.promisify(fs.readdir); | |
| async function read1 (file) { | |
| const label = `read1-${file}`; | |
| console.time(label); | |
| const data = await readFile(file, 'utf8'); | |
| const header = data.split(/\n/)[0]; | |
| console.timeEnd(label); | |
| } | |
| async function read2 (file) { | |
| return new Promise(resolve => { | |
| let header; | |
| const label = `read2-${file}`; | |
| console.time(label); | |
| const stream = fs.createReadStream(file, {encoding: 'utf8'}); | |
| stream.on('data', data => { | |
| header = data.split(/\n/)[0]; | |
| stream.destroy(); | |
| }); | |
| stream.on('close', () => { | |
| console.timeEnd(label); | |
| resolve(); | |
| }); | |
| }); | |
| } | |
| async function startTests(files) { | |
| for (let file of files) { | |
| console.log(file); | |
| await read1(file); | |
| await read2(file); | |
| } | |
| } | |
| readdir(__dirname).then(files => { | |
| startTests(files.filter(file => /dummy\d+\.csv/.test(file))); | |
| }); |
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