New attempt to add helper function to react-jss.

jssSheet2.js

'use strict';

var _ = require('lodash');

// JSS styling
var jss = require('jss').create();

// Order matters!
// https://github.com/jsstyles/jss-camel-case/issues/1
jss.use(require('jss-extend'));
jss.use(require('jss-nested'));
jss.use(require('jss-camel-case'));
jss.use(require('jss-vendor-prefixer'));

var jssReact = require('react-jss')(jss);

module.exports = function() {
    arguments[0].prototype.css = function() {
        var classes = _.get(this, 'props.sheet.classes', {});

        return _.map(arguments, value => {
            if (_.isPlainObject(value))
            {
                return _.chain(value).pick(_.identity).keys().map(value => (classes[value] || value)).value().join(' ');
            }

            if (_.isString(value))
            {
                return classes[value] || value;
            }

            return '';
        }).join(' ');
    };
    return jssReact(...arguments);
};