n array An array of files.
	 */
	private function getManifest() {
		static $file = null;
		if ( $file ) {
			return $file;
		}

		$manifestJson = ''; // This is set in the view.

		if ( file_exists( $this->manifestFile ) ) {
			require_once $this->manifestFile;
		}

		$file = json_decode( $manifestJson, true );

		return $file;
	}

	/**
	 * Get an item from the asset manifest.
	 *
	 * @since 4.1.9
	 *
	 * @param  string      $item An item to retrieve.
	 * @return string|null       The asset item.
	 */
	private function getAssetManifestItem( $item ) {
		$assetManifest = $this->getManifest();

		return ! empty( $assetManifest[ $item ] ) ? $assetManifest[ $item ] : null;
	}

	/**
	 * Get an asset's array of URLs to import.
	 *
	 * @since 4.1.9
	 *
	 * @param  string $asset The asset to find imports for.
	 * @return array         An array of imports.
	 */
	private function importsUrls( $asset ) {
		$urls          = [];
		$manifestAsset = $this->getManifestItem( $asset );
		if ( ! empty( $manifestAsset['imports'] ) ) {
			foreach ( $manifestAsset['imports'] as $import ) {
				$importAsset = $this->getManifestItem( $import );
				if ( ! empty( $importAsset['file'] ) ) {
					$urls[] = $this->getPublicUrlBase() . $importAsset['file'];

					// Load the import's CSS if any.
					$this->loadCss( $import );
				}
			}
		}

		return $urls;
	}

	/**
	 * Returns an asset's CSS urls.
	 *
	 * @since 4.1.9
	 *
	 * @param  string $asset The asset to find CSS URLs for.
	 * @return array         An array of CSS URLs to load.
	 */
	private function getCssUrls( $asset ) {
		$urls          = [];
		$manifestAsset = $this->getManifestItem( $asset );

		if ( ! empty( $manifestAsset['css'] ) ) {
			foreach ( $manifestAsset['css'] as $file ) {
				$urls[ $file ] = $this->getPublicUrlBase() . $file;
			}
		}

		return $urls;
	}

	/**
	 * Check if we should load the dev watcher scripts.
	 *
	 * @since 4.1.9
	 *
	 * @return boolean True if we should load the dev watcher scripts.
	 */
	private function shouldLoadDev() {
		if ( null !== $this->shouldLoadDevScripts ) {
			return $this->shouldLoadDevScripts;
		}

		if (
			! $this->isDev ||
			(
				defined( 'AIOSEO_LOAD_DEV_SCRIPTS' ) &&
				false === AIOSEO_LOAD_DEV_SCRIPTS
			)
		) {
			$this->shouldLoadDevScripts = false;

			return $this->shouldLoadDevScripts;
		}

		if ( ! $this->domain && ! $this->port ) {
			$this->shouldLoadDevScripts = false;

			return $this->shouldLoadDevScripts;
		}

		set_error_handler( function() {} );
		$connection = fsockopen( $this->domain, $this->port ); // phpcs:ignore WordPress.WP.AlternativeFunctions
		restore_error_handler();

		if ( ! $connection ) {
			$this->shouldLoadDevScripts = false;

			return $this->shouldLoadDevScripts;
		}

		$this->shouldLoadDevScripts = true;

		return $this->shouldLoadDevScripts;
	}

	/**
	 * Get the path for the assets.
	 *
	 * @since 4.1.9
	 *
	 * @param  bool   $maybeDev Whether to try and load dev scripts.
	 * @return string           The path for the assets.
	 */
	public function getAssetsPath( $maybeDev = true ) {
		return $maybeDev && $this->shouldLoadDev()
			? $this->getDevUrl()
			: $this->basePath();
	}

	/**
	 * Finds out if a handle should be loaded as regular JS and not as modern JS module.
	 *
	 * @since 4.1.9
	 *
	 * @param  string $handle The script handle.
	 * @return bool           Should the module tag be skipped.
	 */
	public function skipModuleTag( $handle ) {
		if ( ! aioseo()->helpers->stringContains( $handle, $this->jsHandle( '' ) ) ) {
			return true;
		}

		foreach ( $this->noModuleTag as $tag ) {
			if ( aioseo()->helpers->stringContains( $handle, $tag ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Normalize the assets host. Some sites manually set the WP_PLUGINS_URL
	 * and if that domain has www. and the site_url does not, then it will fail to load
	 * our assets. This doesn't fix the issue 100% because it will still fail on
	 * sub-domains that don't have the proper CORS headers. Those sites will need
	 * manual fixes.
	 *
	 * @since 4.1.10
	 *
	 * @param  string $path The path to normalize.
	 * @return string       The normalized path.
	 */
	public function normalizeAssetsHost( $path ) {
		static $paths = [];
		if ( isset( $paths[ $path ] ) ) {
			return apply_filters( 'aioseo_normalize_assets_host', $paths[ $path ] );
		}

		// We need to verify the domain on the $path attribute matches
		// what's in site_url() for our assets or they won't load.
		$siteUrl        = site_url();
		$siteUrlEscaped = aioseo()->helpers->escapeRegex( $siteUrl );
		if ( preg_match( "/^$siteUrlEscaped/i", (string) $path ) ) {
			$paths[ $path ] = $path;

			return apply_filters( 'aioseo_normalize_assets_host', $paths[ $path ] );
		}

		// We now know that the path doesn't contain the site_url().
		$newPath        = $path;
		$siteUrlParsed  = wp_parse_url( $siteUrl );
		$host           = aioseo()->helpers->escapeRegex( str_replace( 'www.', '', $siteUrlParsed['host'] ) );
		$scheme         = aioseo()->helpers->escapeRegex( $siteUrlParsed['scheme'] );

		$siteUrlHasWww = preg_match( "/^{$scheme}:\/\/www\.$host/", (string) $siteUrl );
		$pathHasWww    = preg_match( "/^{$scheme}:\/\/www\.$host/", (string) $path );

		// Check if the path contains www.
		if ( $pathHasWww && ! $siteUrlHasWww ) {
			// If the path contains www., we want to strip it out.
			$newPath = preg_replace( "/^({$scheme}:\/\/)(www\.)($host)/", '$1$3', (string) $path );
		}

		// Check if the site_url contains www.
		if ( $siteUrlHasWww && ! $pathHasWww ) {
			// If the site_url contains www., we want to add it in to the path.
			$newPath = preg_replace( "/^({$scheme}:\/\/)($host)/", '$1www.$2', (string) $path );
		}

		$paths[ $path ] = $newPath;

		return apply_filters( 'aioseo_normalize_assets_host', $paths[ $path ] );
	}

	/**
	 * Get all the CSS files which a JS asset depends on.
	 * This won't work properly unless you've run `npm run build` first.
	 *
	 * @since 4.3.1
	 *
	 * @param  string $asset The asset to find the CSS dependencies for.
	 * @return array         All the asset's CSS dependencies if any.
	 */
	public function getJsAssetCssQueue( $asset ) {
		$queue = [];

		foreach ( $this->getCssUrls( $asset ) as $file => $url ) {
			$queue[] = [
				'handle' => $this->cssHandle( $file ),
				'url'    => $url
			];
		}

		$manifestAsset = $this->getManifestItem( $asset );
		if ( ! empty( $manifestAsset['imports'] ) ) {
			foreach ( $manifestAsset['imports'] as $subAsset ) {
				foreach ( $this->getCssUrls( $subAsset ) as $file => $url ) {
					$queue[] = [
						'handle' => $this->cssHandle( $file ),
						'url'    => $url
					];
				}
			}
		}

		return $queue;
	}
}