cnode-club 的app.js中定义的_.extend(...)是什么意思

// set static, dynamic helpers _.extend(app.locals, { config: config, Loader: Loader, assets: assets });

_.extend(app.locals, require('./common/render_helpers')); app.use(function (req, res, next) { res.locals.csrf = req.csrfToken ? req.csrfToken() : ''; next(); });

_.extend这是什么用法.