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ViewsHow to avoid for await...of with csv-parse
I am looking to be educated on this issue as I have spent a few days trying to resolve it on my own, to no avail.
I am using csv-parse to parse a CSV file.
I am using ESLint as my Linter
I am using the Airbnb JavaScript Style Guide plugin for ESLint
I am running this on the backend using NodeJS
My function is:
const { parse } = require('csv-parse');
const fs = require('fs');
const csvFile = 'myCsvFile.csv';
async function parseCsv(csvFile) {
const records = [];
const parser = fs.createReadStream(csvFile).pipe(parse({ delimiter: ',', columns: true }));
for await (const record of parser) {
records.push(record);
}
return records;
The function works well, however I am trying to abide by Airbnb's Style Guide, which does not like the for await...of loop as it is hitting me with the no-restricted-syntax violation.
I am curious on if there is a better way to write this to fall in line with Airbnb's Style Guide or, if this is one of those situations where it's OK to ignore the violation?
3 answers
Answer question0
The styleguide says:
11.2 Don’t use generators for now. Why? They don’t transpile well to ES5.
Fortunately if you're using a recent NodeJS version, you don't need to transpile down, and can use the engine's native support. For browsers this advice is also outdated soon.
0
How about using events end returning promise?
const { parse } = require('csv-parse');
const fs = require('fs');
const csvFile = 'myCsvFile.csv';
async function parseCsv(csvFile) {
return new Promise((resolve) => {
const records = [];
const stream = fs.createReadStream(csvFile);
const parser = stream.pipe(parse({ delimiter: ',', columns: true }));
parser.on('readable', () => {
while (record = parser.read()) {
records.push(record);
}
});
let ended = false;
const end = (error) => {
if (error) {
console.error(error.message);
}
if (!ended) {
ended = true;
resolve(records);
}
};
parser.on('error', end);
parser.on('end', end);
});
}
also if You have node 15+ then try stream/promises example:
const { parse } = require('csv-parse');
const fs = require('fs');
const { finished } = require('stream/promises');
const csvFile = 'myCsvFile.csv';
async function parseCsv(csvFile) {
const records = [];
const stream = fs.createReadStream(csvFile);
const parser = stream.pipe(parse({ delimiter: ',', columns: true }));
parser.on('readable', () => {
let record;
while ((record = parser.read()) !== null) {
records.push(record);
}
});
await finished(parser);
return records;
}
0
Based on advice given in the answers, I am going to ignore the Airbnb Style Guide and use the Async iterator method.
Final code:
const { parse } = require('csv-parse');
const fs = require('fs');
const path = require('path');
const debug = require('debug')('app:csv:service');
const chalk = require('chalk');
async function parseCsv(csvFile) {
try {
const records = [];
const stream = fs.createReadStream(csvFile);
const parser = stream.pipe(parse({ delimiter: ',', columns: true }));
// eslint-disable-next-line no-restricted-syntax
for await (const record of parser) {
records.push(record);
}
return records;
} catch (error) {
debug(`${chalk.red('Failed')} to parse CSV`);
debug(`${chalk.red('ERROR:')} ${error}`);
throw error;
}
}
It may be time to find a new Style Guide to follow. Thank you to num8er for the code advice (I took one of your ideas to make my code a little more readable).