Inconsistent translations populated in the js-translation.json

Question

Can anyone please shed some light on the js-translation.json and where it pulls the phrases in from?

We have a Spanish store view and we have 934 phrases translated in our app/i18n/vendor/es_es/es_ES.csv language package.

We also have custom modules, some of which include translations in their app/code/Vendor/ModuleName/i18n/es_ES.csv

After setup:static-content:deploy es_ES (and all caches cleared etc etc) the js-translation.json file generates and IS populated but it only contains 194 phrases, some of which are specifically from custom modules, some of which are from the main language package.

If a phrase is included in the js-translation.json which has come from a custom module I would expect all phrases from that custom module would be included, but this is not the case.

I would also expect that if the js-translation.json contains phrases from the main language package then it would contain them all, which is not the case.

I can confirm that ALL translations are actually working on the frontend but my question is why are only some translations included in the js-translation.json and not all?

Thanks in advance for any light you can shed on this!

Answer 1

Turns out that only phrases rendered in javascript or html templates are included in the js-translation.json.

If you look in vendor/magento/module-translation/etc/di.xml you will see the regex which retrieves these:

<type name="Magento\Translation\Model\Js\Config">
    <arguments>
        <argument name="patterns" xsi:type="array">
            <item name="i18n_translation" xsi:type="string"><![CDATA[~i18n\:\s*(["'])(.*?)(?<!\\)\1~]]></item>
            <item name="translate_wrapping" xsi:type="string"><![CDATA[~translate\=("')([^\'].*?)\'\"~]]></item>
            <item name="mage_translation_widget" xsi:type="string"><![CDATA[~(?:\$|jQuery)\.mage\.__\((?s)[^'"]*?(['"])(.+?)(?<!\\)\1(?s).*?\)~]]></item>
            <item name="mage_translation_static" xsi:type="string"><![CDATA[~\$t\((?s)[^'"]*?(["'])(.+?)\1(?s).*?\)~]]></item>
        </argument>
    </arguments>
</type>

Thanks to Vinai Kopp!