Issue #3238915: Refactor (if feasible) uses of the jQuery ready function to use VanillaJS

core/lib/Drupal/Core/Utility/PhpRequirements.php

+<?php
+
+namespace Drupal\Core\Utility;
+
+/**
+ * Provides an object for dynamically identifying the minimum supported PHP.
+ */
+final class PhpRequirements {
+
+  /**
+   * The minimum PHP version requirement for the installed Drupal version.
+   *
+   * This property is maintained to make the class testable.
+   *
+   * @var string
+   *
+   * @see version_compare()
+   */
+  private static $drupalMinimumPhp = \Drupal::MINIMUM_PHP;
+
+  /**
+   * The expected PHP version end-of-life dates, keyed by PHP minor version.
+   *
+   * The array keys are in 'major.minor' format, and the date values are in ISO
+   * 8601 format.
+   *
+   * @var string[]
+   *   An array of end-of-life dates in ISO 8601 format, keyed by the PHP minor
+   *   version in 'major.minor' format. The list must be sorted in an ascending
+   *   order by the date. Multiple versions EOL on the same day must be sorted
+   *   by the PHP version.
+   */
+  private static $phpEolDates = [
+    '7.3' => '2021-12-06',
+    '7.4' => '2022-11-28',
+    '8.0' => '2023-11-26',
+    '8.1' => '2024-11-25',
+  ];
+
+  /**
+   * This class should not be instantiated.
+   */
+  private function __construct() {
+  }
+
+  /**
+   * Dynamically identifies the minimum supported PHP version based on the date.
+   *
+   * Drupal automatically increases the minimum supported PHP version from
+   * \Drupal::MINIMUM_PHP to a newer version after PHP's documented end-of-life
+   * date for the previous version.
+   *
+   * Below this version:
+   * - New sites can be installed (to allow update deployment workflows that
+   *   reinstall sites from configuration), but a warning is displayed in the
+   *   installer that the PHP version is too old (except within tests).
+   * - Updates from previous Drupal versions can be run, but users are warned
+   *   that Drupal no longer supports that PHP version.
+   * - An error is shown in the status report that the PHP version is too old.
+   *
+   * @param \DateTime|null $date
+   *   The DateTime to check. Defaults to the current datetime (now) if NULL.
+   *
+   * @return string
+   *   The minimum supported PHP version on the date in a PHP-standardized
+   *   number format supported by version_compare(). For example, '8.0.2' or
+   *   '8.1'. This will be the lowest PHP version above the minimum PHP version
+   *   supported by Drupal that is still supported, or the highest known PHP
+   *   version if no known versions are still supported.
+   *
+   * @see version_compare()
+   */
+  public static function getMinimumSupportedPhp(?\DateTime $date = NULL): string {
+    // By default, use the current date (right now).
+    $date = $date ?? new \DateTime('now');
+
+    // In case no data are available or all known PHP versions in this class
+    // are already end-of-life, default to the version that had the most recent
+    // end-of-life (the key of the last element in the sorted array).
+    // The string cast ensures the value is a string, even if the PHP EOL date
+    // array is empty. As of PHP 8.1, version_compare() no longer accepts NULL
+    // as a parameter; empty string must be used instead.
+    $lowest_supported_version = $lowest_supported_version ?? (string) array_key_last(static::$phpEolDates);
+
+    // Next, look at versions that are end-of-life after the current date.
+    // Find the lowest PHP version that is still supported.
+    foreach (static::$phpEolDates as $version => $eol_date) {
+      $eol_datetime = new \DateTime($eol_date);
+
+      if ($eol_datetime > $date) {
+        // If $version is less than the previously discovered lowest supported
+        // version, use $version as the lowest supported version instead.
+        if (version_compare($version, $lowest_supported_version) < 0) {
+          $lowest_supported_version = $version;
+        }
+      }
+    }
+
+    // If PHP versions older than the Drupal minimum PHP version are still
+    // supported, return Drupal minimum PHP version instead.
+    if (version_compare($lowest_supported_version, static::$drupalMinimumPhp) < 0) {
+      return static::$drupalMinimumPhp;
+    }
+
+    // Otherwise, return the lowest supported PHP version.
+    return $lowest_supported_version;
+  }
+
+}