Run this in the Figma console to export a .js file with locally defined shared styles

get-figma-local-styles

(function() {

    const styles = [];
    const addStyle = style => {
        const rawToken = style.name.match(/\([^()]+\)(?=[^()]*$)/);
        let token = null;
        if (rawToken && rawToken[0] !== '(Underline)') {
            token = `--${rawToken[0].split('(')[1].split(')')[0]}`
        }

        styles.push({
            ...style,
            name: style.name,
            description: style.description,
            key: style.key,
            type: style.type,
            token
        })
    }

    const textStyles = figma.getLocalTextStyles();
    const paintStyles = figma.getLocalPaintStyles();
    const gridStyles = figma.getLocalGridStyles();
    const effectStyles = figma.getLocalEffectStyles();

    textStyles.forEach(sty => addStyle(sty));
    paintStyles.forEach(sty => addStyle(sty));
    gridStyles.forEach(sty => addStyle(sty));
    effectStyles.forEach(sty => addStyle(sty));

    const fileContent = `module.exports = ${JSON.stringify(styles, null, 2)}`

    const download = (content, fileName, contentType) => {
        const a = document.createElement("a");
        const file = new Blob([content], {type: contentType});
        a.href = URL.createObjectURL(file);
        a.download = fileName;
        a.click();
    }

    download(fileContent, 'tokens.js', 'text/javascript');

})();