title: _.isFunction(a) vs. typeof a === 'function'? javascript
body: <p>I think it might be only performance case - <a href="http://jsperf.com/comparing-underscore-js-isfunction-with-typeof-function/2">http://jsperf.com/comparing-underscore-js-isfunction-with-typeof-function/2</a></p>
  
  <p>And seems that <code>typeof</code> is faster.. so my question is - which is more appropriate to use?</p>