Source

File: wp-includes/l10n.php

function load_script_textdomain( $handle, $domain = 'default', $path = null ) {
	$wp_scripts = wp_scripts();

	if ( ! isset( $wp_scripts->registered[ $handle ] ) ) {
		return false;
	}

	$path   = untrailingslashit( $path );
	$locale = determine_locale();

	// If a path was given and the handle file exists simply return it.
	$file_base       = 'default' === $domain ? $locale : $domain . '-' . $locale;
	$handle_filename = $file_base . '-' . $handle . '.json';

	if ( $path ) {
		$translations = load_script_translations( $path . '/' . $handle_filename, $handle, $domain );

		if ( $translations ) {
			return $translations;
		}
	}

	$src = $wp_scripts->registered[ $handle ]->src;

	if ( ! preg_match( '|^(https?:)?//|', $src ) && ! ( $wp_scripts->content_url && 0 === strpos( $src, $wp_scripts->content_url ) ) ) {
		$src = $wp_scripts->base_url . $src;
	}

	$relative       = false;
	$languages_path = WP_LANG_DIR;

	$src_url     = wp_parse_url( $src );
	$content_url = wp_parse_url( content_url() );
	$plugins_url = wp_parse_url( plugins_url() );
	$site_url    = wp_parse_url( site_url() );

	// If the host is the same or it's a relative URL.
	if (
		( ! isset( $content_url['path'] ) || strpos( $src_url['path'], $content_url['path'] ) === 0 ) &&
		( ! isset( $src_url['host'] ) || $src_url['host'] === $content_url['host'] )
	) {
		// Make the src relative the specific plugin or theme.
		if ( isset( $content_url['path'] ) ) {
			$relative = substr( $src_url['path'], strlen( $content_url['path'] ) );
		} else {
			$relative = $src_url['path'];
		}
		$relative = trim( $relative, '/' );
		$relative = explode( '/', $relative );

		$languages_path = WP_LANG_DIR . '/' . $relative[0];

		$relative = array_slice( $relative, 2 ); // Remove plugins/<plugin name> or themes/<theme name>.
		$relative = implode( '/', $relative );
	} elseif (
		( ! isset( $plugins_url['path'] ) || strpos( $src_url['path'], $plugins_url['path'] ) === 0 ) &&
		( ! isset( $src_url['host'] ) || $src_url['host'] === $plugins_url['host'] )
	) {
		// Make the src relative the specific plugin.
		if ( isset( $plugins_url['path'] ) ) {
			$relative = substr( $src_url['path'], strlen( $plugins_url['path'] ) );
		} else {
			$relative = $src_url['path'];
		}
		$relative = trim( $relative, '/' );
		$relative = explode( '/', $relative );

		$languages_path = WP_LANG_DIR . '/plugins';

		$relative = array_slice( $relative, 1 ); // Remove <plugin name>.
		$relative = implode( '/', $relative );
	} elseif ( ! isset( $src_url['host'] ) || $src_url['host'] === $site_url['host'] ) {
		if ( ! isset( $site_url['path'] ) ) {
			$relative = trim( $src_url['path'], '/' );
		} elseif ( ( strpos( $src_url['path'], trailingslashit( $site_url['path'] ) ) === 0 ) ) {
			// Make the src relative to the WP root.
			$relative = substr( $src_url['path'], strlen( $site_url['path'] ) );
			$relative = trim( $relative, '/' );
		}
	}

	/**
	 * Filters the relative path of scripts used for finding translation files.
	 *
	 * @since 5.0.2
	 *
	 * @param string|false $relative The relative path of the script. False if it could not be determined.
	 * @param string       $src      The full source URL of the script.
	 */
	$relative = apply_filters( 'load_script_textdomain_relative_path', $relative, $src );

	// If the source is not from WP.
	if ( false === $relative ) {
		return load_script_translations( false, $handle, $domain );
	}

	// Translations are always based on the unminified filename.
	if ( substr( $relative, -7 ) === '.min.js' ) {
		$relative = substr( $relative, 0, -7 ) . '.js';
	}

	$md5_filename = $file_base . '-' . md5( $relative ) . '.json';

	if ( $path ) {
		$translations = load_script_translations( $path . '/' . $md5_filename, $handle, $domain );

		if ( $translations ) {
			return $translations;
		}
	}

	$translations = load_script_translations( $languages_path . '/' . $md5_filename, $handle, $domain );

	if ( $translations ) {
		return $translations;
	}

	return load_script_translations( false, $handle, $domain );
}