diff --git a/lib/allProperties.js b/lib/allProperties.js
index d9fffb3..6347745 100644
--- a/lib/allProperties.js
+++ b/lib/allProperties.js
@@ -1,11 +1,6 @@
 'use strict';
-
-// autogenerated - 9/7/2024
-
-/*
- *
- * https://www.w3.org/Style/CSS/all-properties.en.html
- */
+// autogenerated - 2024-09-07
+// https://www.w3.org/Style/CSS/all-properties.en.html
 
 module.exports = new Set([
   '-webkit-line-clamp',
@@ -126,7 +121,6 @@ module.exports = new Set([
   'caret',
   'caret-color',
   'caret-shape',
-  'chains',
   'clear',
   'clip',
   'clip-path',
@@ -180,7 +174,6 @@ module.exports = new Set([
   'float',
   'flood-color',
   'flood-opacity',
-  'flow',
   'flow-from',
   'flow-into',
   'font',
diff --git a/package.json b/package.json
index 40b01c9..59881d2 100644
--- a/package.json
+++ b/package.json
@@ -53,9 +53,9 @@
     "resolve": "^1.22.1"
   },
   "scripts": {
-    "download": "node ./scripts/download_latest_properties.js && eslint lib/allProperties.js --fix",
+    "download": "node ./scripts/downloadLatestProperties.mjs && eslint lib/allProperties.js --fix",
     "generate": "run-p generate:*",
-    "generate:implemented_properties": "node ./scripts/generate_implemented_properties.js",
+    "generate:implemented_properties": "node ./scripts/generateImplementedProperties.mjs",
     "generate:properties": "node ./scripts/generate_properties.js",
     "lint": "npm run generate && eslint --max-warnings 0",
     "lint:fix": "eslint --fix --max-warnings 0",
diff --git a/scripts/downloadLatestProperties.mjs b/scripts/downloadLatestProperties.mjs
new file mode 100644
index 0000000..703c42c
--- /dev/null
+++ b/scripts/downloadLatestProperties.mjs
@@ -0,0 +1,52 @@
+// The W3C CSSWG provides a JSON list of all CSS properties and their status in the standard.
+// See the documentation at https://www.w3.org/Style/CSS/all-properties.en.html.
+//
+// This script downloads that file and uses it to write an appropriately-filtered Set of property
+// names to a file.
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const url = 'https://www.w3.org/Style/CSS/all-properties.en.json';
+const outputFile = resolve('../lib/allProperties.js');
+const unwantedStatuses = new Set(['NOTE', 'ED', 'FPWD']);
+
+console.log('Downloading CSS properties...');
+
+const res = await fetch(url);
+if (res.status !== 200) {
+  throw new Error('Bad status code: ' + res.status);
+}
+
+const rawCSSProperties = await res.json();
+
+const propertyNames = new Set();
+for (const cssProp of rawCSSProperties) {
+  // Filter out properties from too-new statuses.
+  // Also, '--*' needs additional logic to this module, so filter it out for now.
+  if (unwantedStatuses.has(cssProp.status) || cssProp.property === '--*') {
+    continue;
+  }
+
+  propertyNames.add(cssProp.property);
+}
+
+const propertyNamesJSON = JSON.stringify(Array.from(propertyNames), undefined, 2);
+const dateToday = new Date();
+const dateTodayFormatted = dateToday.toISOString().split('T')[0];
+
+const output = `
+'use strict';
+// autogenerated - ${dateTodayFormatted}
+// https://www.w3.org/Style/CSS/all-properties.en.html
+
+module.exports = new Set(${propertyNamesJSON});
+`;
+
+fs.writeFileSync(outputFile, output);
+
+// TODO: remove when we can drop Node.js 18 support and use import.meta.dirname.
+function resolve(relativePath) {
+  return path.resolve(path.dirname(fileURLToPath(import.meta.url)), relativePath);
+}
diff --git a/scripts/download_latest_properties.js b/scripts/download_latest_properties.js
deleted file mode 100644
index d63fa2b..0000000
--- a/scripts/download_latest_properties.js
+++ /dev/null
@@ -1,90 +0,0 @@
-'use strict';
-
-/*
- * W3C provides JSON list of all CSS properties and their status in the standard
- *
- * documentation: https://www.w3.org/Style/CSS/all-properties.en.html
- * JSON url: ( https://www.w3.org/Style/CSS/all-properties.en.json )
- *
- * Download that file, filter out duplicates and filter the properties based on the wanted standard level
- *
- * ED   - Editors' Draft (not a W3C Technical Report)
- * FPWD - First Public Working Draft
- * WD   - Working Draft
- * LC   - Last Call Working Draft
- * CR   - Candidate Recommendation
- * PR   - Proposed Recommendation
- * REC  - Recommendation
- * NOTE - Working Group Note
- */
-
-var fs = require('fs');
-var path = require('path');
-
-const { camelToDashed } = require('../lib/parsers');
-
-var url = 'https://www.w3.org/Style/CSS/all-properties.en.json';
-
-function toCamelCase(propName) {
-  return propName.replace(/-([a-z])/g, function (g) {
-    return g[1].toUpperCase();
-  });
-}
-
-async function main() {
-  console.log('Downloading CSS properties...');
-
-  const res = await fetch(url);
-  if (res.status !== 200) {
-    throw new Error('Bad status code: ' + res.status);
-  }
-
-  const allCSSProperties = await res.json();
-
-  // Filter out all properties newer than Working Draft
-  var workingDraftAndOlderProperties = allCSSProperties.filter(function (cssProp) {
-    // TODO: --* css Needs additional logic to this module, so filter it out for now
-    return cssProp.status !== 'ED' && cssProp.status !== 'FPWD' && cssProp.property !== '--*';
-  });
-
-  // Remove duplicates, there can be many properties in different states of standard
-  // and add only property names to the list
-  var CSSpropertyNames = [];
-  workingDraftAndOlderProperties.forEach(function (cssProp) {
-    const camelCaseName = toCamelCase(cssProp.property);
-
-    if (CSSpropertyNames.indexOf(camelCaseName) === -1) {
-      CSSpropertyNames.push(camelCaseName);
-    }
-  });
-
-  var out_file = fs.createWriteStream(path.resolve(__dirname, './../lib/allProperties.js'), {
-    encoding: 'utf-8',
-  });
-
-  var date_today = new Date();
-  out_file.write(
-    "'use strict';\n\n// autogenerated - " +
-      (date_today.getMonth() + 1 + '/' + date_today.getDate() + '/' + date_today.getFullYear()) +
-      '\n\n'
-  );
-  out_file.write('/*\n *\n * https://www.w3.org/Style/CSS/all-properties.en.html\n */\n\n');
-  out_file.write(
-    'module.exports = new Set(' +
-      JSON.stringify(CSSpropertyNames.map(camelToDashed), null, 2) +
-      ');\n'
-  );
-
-  out_file.end(function (err) {
-    if (err) {
-      throw err;
-    }
-
-    console.log('Generated ' + Object.keys(CSSpropertyNames).length + ' properties.');
-  });
-}
-
-main().catch((e) => {
-  console.error(e.stack);
-  process.exit(1);
-});
diff --git a/scripts/generateImplementedProperties.mjs b/scripts/generateImplementedProperties.mjs
new file mode 100644
index 0000000..54a3a1d
--- /dev/null
+++ b/scripts/generateImplementedProperties.mjs
@@ -0,0 +1,30 @@
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { camelToDashed } from '../lib/parsers.js';
+
+const dashedProperties = fs
+  .readdirSync(resolve('../lib/properties'))
+  .filter((propertyFile) => path.extname(propertyFile) === '.js')
+  .map((propertyFile) => camelToDashed(path.basename(propertyFile, '.js')));
+
+const outputFile = resolve('../lib/implementedProperties.js');
+
+const propertyNamesJSON = JSON.stringify(dashedProperties, undefined, 2);
+const dateToday = new Date();
+const dateTodayFormatted = dateToday.toISOString().split('T')[0];
+
+const output = `
+'use strict';
+// autogenerated - ${dateTodayFormatted}
+// https://www.w3.org/Style/CSS/all-properties.en.html
+
+module.exports = new Set(${propertyNamesJSON});
+`;
+
+fs.writeFileSync(outputFile, output);
+
+// TODO: remove when we can drop Node.js 18 support and use import.meta.dirname.
+function resolve(relativePath) {
+  return path.resolve(path.dirname(fileURLToPath(import.meta.url)), relativePath);
+}
diff --git a/scripts/generate_implemented_properties.js b/scripts/generate_implemented_properties.js
deleted file mode 100644
index 2407fd9..0000000
--- a/scripts/generate_implemented_properties.js
+++ /dev/null
@@ -1,61 +0,0 @@
-'use strict';
-
-const fs = require('fs');
-const path = require('path');
-const t = require('@babel/types');
-const generate = require('@babel/generator').default;
-const camelToDashed = require('../lib/parsers').camelToDashed;
-
-const dashedProperties = fs
-  .readdirSync(path.resolve(__dirname, '../lib/properties'))
-  .filter((propertyFile) => propertyFile.substr(-3) === '.js')
-  .map((propertyFile) => camelToDashed(propertyFile.replace('.js', '')));
-
-const out_file = fs.createWriteStream(path.resolve(__dirname, '../lib/implementedProperties.js'), {
-  encoding: 'utf-8',
-});
-var date_today = new Date();
-out_file.write(
-  "'use strict';\n\n// autogenerated - " +
-    (date_today.getMonth() + 1 + '/' + date_today.getDate() + '/' + date_today.getFullYear()) +
-    '\n\n'
-);
-out_file.write('/*\n *\n * https://www.w3.org/Style/CSS/all-properties.en.html\n */\n\n');
-
-const statements = [];
-statements.push(
-  t.variableDeclaration('var', [
-    t.variableDeclarator(
-      t.identifier('implementedProperties'),
-      t.newExpression(t.identifier('Set'), [])
-    ),
-  ])
-);
-
-dashedProperties.forEach((property) => {
-  statements.push(
-    t.expressionStatement(
-      t.callExpression(
-        t.memberExpression(t.identifier('implementedProperties'), t.identifier('add')),
-        [t.stringLiteral(property)]
-      )
-    )
-  );
-});
-
-statements.push(
-  t.expressionStatement(
-    t.assignmentExpression(
-      '=',
-      t.memberExpression(t.identifier('module'), t.identifier('exports')),
-      t.identifier('implementedProperties')
-    )
-  )
-);
-
-out_file.write(generate(t.program(statements)).code + '\n');
-out_file.end(function (err) {
-  if (err) {
-    throw err;
-  }
-});