nomilo/assets/scripts/l10n.js

async function l10n(key, args = undefined) {
    if (window.fluentBundle === undefined) {
        const lang = document.documentElement.lang;
        const bundle = new FluentBundle.FluentBundle(lang);

        const promises = [...document.querySelectorAll('[data-l10n]')]
            .map(link => fetch(link.href)
                    .then(res => res.text())
                    .then(data => new FluentBundle.FluentResource(data))
            );


        const resources = await Promise.all(promises);

        for (const resource of resources) {
            bundle.addResource(resource);
        }

        window.fluentBundle = bundle;
    }

    const [messageId, messageAttribute] = key.split('.')

    const message = window.fluentBundle.getMessage(messageId);

    if (message) {
        const errors = [];
        let pattern;

        if (messageAttribute !== undefined) {
            pattern = message.attributes[messageAttribute]
        } else {
            pattern = message.value;
        }

        if (pattern) {
            const message = window.fluentBundle.formatPattern(pattern, args, errors)
            if (errors.length > 0) {
                for (const error of errors) {
                    console.error(`[localization error]: ${error}`)
                }
            }
            return message
        } else {
            return messageAttribute ? `{${messageId}.${messageAttribute}}` : `{${messageId}}`;
        }
    } else {
        return messageAttribute ? `{${messageId}.${messageAttribute}}` : `{${messageId}}`;
    }

}