Detect the latest ECMAScript version supported by JavascriptCore on macOS

detect.sh

#!/usr/bin/env sh

# Find the jsc REPL, and execute our detection code inside it.

SCRIPT_DIR="$( cd "$( dirname "$0" )" && pwd )"

JSC=$(find -H /System/Library/Frameworks/JavaScriptCore.framework -iname jsc)

if [ -z "$JSC" ]; then
    echo "jsc binary not found" >&2
    exit 1
fi

echo "Using jsc at $JSC"

$JSC "$SCRIPT_DIR/detect_js_version.js"

detect_js_version.js

// Adapted from https://stackoverflow.com/a/68953809/404321
// https://www.devdiscuss.com/how-to-detect-the-ecmascript-version/
//
// Adapted and shared under CC BY-SA 4.0

var getECMAVersion = function () {
  var rv = '';

  // https://en.wikipedia.org/wiki/ECMAScript_version_history
  return (
    (rv = null),
    'function' == typeof RegExp &&
      (rv = {
        edition: 3,
        date_published: '1999-12'
      }),
    'function' == typeof Array.isArray &&
      (rv = {
        edition: 5,
        date_published: '2009-12'
      }),
    ('function' != typeof Array.find && 'function' != typeof Array.findIndex) ||
      (rv = {
        edition: 6,
        date_published: '2015-06',
        name: 'ECMAScript 2015',
        name_code: 'ES2015'
      }),
    'function' == typeof Array.prototype.includes &&
      (rv = {
        edition: 7,
        date_published: '2016-06',
        name: 'ECMAScript 2016',
        name_code: 'ES2016'
      }),
    'function' == typeof Object.entries &&
      (rv = {
        edition: 8,
        date_published: '2017-06',
        name: 'ECMAScript 2017',
        name_code: 'ES2017'
      }),
    'undefined' != typeof Promise &&
      'function' == typeof Promise.prototype.finally &&
      (rv = {
        edition: 9,
        date_published: '2018-06',
        name: 'ECMAScript 2018',
        name_code: 'ES2018'
      }),
    ('function' != typeof Object.fromEntries && 'function' != typeof String.prototype.trimStart) ||
      (rv = {
        edition: 10,
        date_published: '2019-06',
        name: 'ECMAScript 2019',
        name_code: 'ES2019'
      }),
    'function' == typeof BigInt &&
      (rv = {
        edition: 11,
        date_published: '2020-06',
        name: 'ECMAScript 2020',
        name_code: 'ES2020'
      }),
    'function' == typeof String.prototype.replaceAll &&
      (rv = {
        edition: 12,
        date_published: '2021-06',
        name: 'ECMAScript 2021',
        name_code: 'ES2021'
      }),
    'function' == typeof Object.hasOwn &&
      (rv = {
        edition: 13,
        date_published: '2022-06',
        name: 'ECMAScript 2022',
        name_code: 'ES2022'
      }),
    'function' == typeof Array.prototype.toSorted &&
      (rv = {
        edition: 14,
        date_published: '2023-06',
        name: 'ECMAScript 2023',
        name_code: 'ES2023'
      }),
    rv
  );
};

// https://gist.github.com/ctkjose/03d14236a55c4b85cb8d6e6156c57b13
var console = { log: debug };

var ecma = getECMAVersion();

if (typeof ecma !== 'undefined') {
  if (ecma.edition) {
    console.log('ECMAScript Edition: ' + ecma.edition);
  }

  if (ecma.name) {
    console.log('Name: ' + ecma.name);
  }

  if (ecma.date_published) {
    console.log('Released: ' + ecma.date_published);
  }
}