npm download counts for a package using npm stats. Hardcoded for 2023

npm-download-counts-for-pkg.js

const fs = require("fs");

async function getDownloadsPerDay(pkgName) {
  // for the past year
  const from = "2022-12-01";
  const until = "2023-11-30";
  try {
    const res = await fetch(
      `https://npm-stat.com/api/download-counts?package=${pkgName}&from=${from}&until=${until}`,
    );
    const json = await res.json();
    return json;
  } catch (error) {
    console.error(`Error fetching downloads: ${error.message}`);
    throw error;
  }
}

function writeToCSV(monthlyDownloads, packageName) {
  const csvData = [["date", "downloads"]];

  for (const [date, downloadCount] of Object.entries(monthlyDownloads)) {
    csvData.push([date, downloadCount]);
  }

  const csvString = csvData.map((row) => row.join(",")).join("\n");
  const filename = `${packageName}-monthly-downloads.csv`;
  fs.writeFileSync(filename, csvString, "utf-8");

  console.log(`CSV data has been saved to ${filename}`);
}

function convertToMonthlyDownloads(dailyData) {
  const monthlyData = {};

  for (const date in dailyData) {
    const [year, month] = date.split("-");
    const day = "15"; // use middle of month for scatter plot
    const yearMonth = `${year}-${month}-${day}`;

    if (monthlyData[yearMonth]) {
      monthlyData[yearMonth] += dailyData[date];
    } else {
      monthlyData[yearMonth] = dailyData[date];
    }
  }

  return monthlyData;
}

function calculatePercentChange(monthlyDownloads) {
  const dates = Object.keys(monthlyDownloads);
  const firstDate = dates[0];
  const lastDate = dates[dates.length - 1];

  const firstCount = monthlyDownloads[firstDate];
  const lastCount = monthlyDownloads[lastDate];

  const percentChange = ((lastCount - firstCount) / firstCount) * 100;
  console.log("percentChange: ", `${percentChange.toFixed(2)}%`);
}

async function main() {
  const pkgName = process.argv[2];

  const downloads = await getDownloadsPerDay(pkgName);
  const monthlyDownloads = convertToMonthlyDownloads(downloads[pkgName]);
  calculatePercentChange(monthlyDownloads);

  writeToCSV(monthlyDownloads, pkgName);
}

main();