Performance improvement - RegExp caching

[oliverfoster]

json2csv v7.0.4, in node v16.20.2

json2csv/dist/cdn/formatters/string.js

Lines 2 to 17 in 2c36527

	function stringFormatter(opts = {}) {
	const quote = typeof opts.quote === "string" ? opts.quote : '"';
	const escapedQuote = typeof opts.escapedQuote === "string" ? opts.escapedQuote : `${quote}${quote}`;
	if (!quote || quote === escapedQuote) {
	return (value) => value;
	}
	return (value) => {
	if (value.includes(quote)) {
	value = value.replace(new RegExp(quote, "g"), escapedQuote);
	}
	return `${quote}${value}${quote}`;
	};
	}
	export {
	stringFormatter as default
	};

Can be replaced with:

// packages/formatters/src/string.ts
function stringFormatter(opts = {}) {
  const quote = typeof opts.quote === "string" ? opts.quote : '"';
  const escapedQuote = typeof opts.escapedQuote === "string" ? opts.escapedQuote : `${quote}${quote}`;
  if (!quote || quote === escapedQuote) {
    return (value) => value;
  }
  const cachedRex = new RegExp(quote, "g");
  return (value) => {
    if (value.includes(quote)) {
      value = value.replace(cachedRex, escapedQuote);
    }
    return `${quote}${value}${quote}`;
  };
}
export {
  stringFormatter as default
};

The performance improvement can be seen using:

import Benchmark from 'benchmark'

const quote = "\""
const escapedQuote = "'"
const cached = new RegExp(quote, 'g')

const suite = new Benchmark.Suite
suite
  .add('uncached', function () {
    const rex = new RegExp(quote, 'g')
    const str = "tes\"ting".replace(rex, escapedQuote)
  })
  .add('cached', function () {
    const str = "tes\"ting".replace(cached, escapedQuote)
  })
  // add listeners
  .on('cycle', function(event) {
    console.log(String(event.target));
  })
  .on('complete', function() {
    console.log('Fastest is ' + this.filter('fastest').map('name'));
  })
  // run async
  .run({ 'async': true });

Performance:

[juanjoDiaz]

Great suggestion!

[oliverfoster]

Fixed in dcaadcf

🥳