Update to support makepot logic run against JavaScript files

[bobbingwide]

The WordPress block editor ( Gutenberg ) allows plugins and themes to be developed in JavaScript. Text strings written in the JavaScript (REACT) files should be translatable. WP-cli provides an i18n make-pot subcommand that enables the PHP and JavaScript strings used in the WordPress approved internationalization functions to be extracted to the main .pot file.
It also provides the i18n make-json subcommand to extract the Javascript strings from translated .po files into 'json files.
See notes to documentation below.

Requirement

• Update the l10n routine to extract translatable text strings from JavaScript files so that the translated versions can be delivered to the end user's browser and displayed in their preferred language.
• It'll also be necessary to update each plugin to use wp_set_script_translations. See Prototype a Breadcrumbs block supporting internationalization sb-breadcrumbs-block#1

Proposed solution

There are a couple of alternative

• Change the do_makeoik() function to call the same logic as wp-cli
• Change the do_makeoik() function to not bother to rebuild the .pot file that was generated using the wp-cli method.

Notes:

• In plugins which generate blocks we can add the npm run makepot command to build the main .pot file

package.json would include a line like this

"makepot": "wp i18n make-pot . languages/sb-breadcrumbs-block.pot --exclude=node_modules,vendor,build"

See also https://developer.wordpress.org/cli/commands/i18n/make-json/
to find out if we can use the i18n make-json subcommand instead.
....We only need to enqueue the strings that are needed in the editor.

and https://getwithgutenberg.com/2019/04/how-to-internationalize-your-block/

Original documentation which talks about md5... but which I don't understand...

https://make.wordpress.org/core/2018/11/09/new-javascript-i18n-support-in-wordpress/

[bobbingwide]

package.json would include a line like this

"makepot": "wp i18n make-pot . languages/sb-breadcrumbs-block.pot --exclude=node_modules,vendor,build"

Further investigation indicated that the .js files that we need to scan are those in the build directory, not the src ( source ).
So we need to change the exclude= parameter.

"makepot": "wp i18n make-pot . languages/sb-breadcrumbs-block.pot --exclude=node_modules,vendor,src"

The semi-automatic process for localization into en_GB and bb_BB locales is:

Command	Explanation
npm start or npm run build	to build the block: target file build/index.js
npm run makepot	to build the main .pot file in the languages folder
l10n	my localization routine to build .po and .mo files for en_GB and bb_BB in languages folder
npm run makejson	to build the .json file(s) to match the build.index.js script; one for each locale.

For the sb-breadcrumbs-block plugin the target JSON files are:

• sb-breadcrumbs-block-bb_BB-dfbff627e6c248bcb3b61d7d06da9ca9.json
• sb-breadcrumbs-block-en_GB-dfbff627e6c248bcb3b61d7d06da9ca9.json

where md5 for build/index.js is dfbff627e6c248bcb3b61d7d06da9ca9

Using this process means I don't need to rename the .json files in order for WordPress to find them.
The code that's needed to localise the JavaScript file that's enqueued in the block editor is:

/*
 * Localise the script by loading the required strings for the build/index.js file
 * from the locale specific .json file in the languages folder
 */
	$ok = wp_set_script_translations( 'sb-breadcrumbs-block-block-editor', 'sb-breadcrumbs-block' , $dir .'/languages'  );

where

• 'sb-breadcrumbs-block-block-editor' is the handle used to register the script.
• 'sb-breadcrumbs-block' is the text domain
• $dir.'/languages' - is the fully qualified path the the languages folder

[bobbingwide]

Change the do_makeoik() function to not bother to rebuild the .pot file that was generated using the wp-cli method.

For the sb-children-block plugin I changed the logic to skip calling do_makeoik().
In the future the logic should be changed to test for the presence of a node_modules folder which suggests the presence of Javascript that needs to be translated.

Update 2020/09/04
The logic will need to take into account plugins where the blocks are not built from the src folder.
The function is maybe_do_makeoik

node_modules	src	Process to use
n	n	makeoik
n	y	makeoik -
y	n	makeoik - but JavaScipt blocks are not internationalised
y	y	npm run makepot & npm run l10n & npm run makejson

Additional functions are needed to copy the plugin's .pot file to and from oik-i18n/working depending on which process is used to build the file.

Note: In the plugin's package.json file npm run makepot needs to be configured to ignore the src folder and use the build folder for the source of .js files to be searched for strings.

[bobbingwide]

I believe this can now be closed.