React onClick and preventDefault() link refresh/redirect?

I'm rendering a link with react:

render: ->
  `<a className="upvotes" onClick={this.upvote}>upvote</a>`

Then, above I have the upvote function:

upvote: ->
  // do stuff (ajax)

Before link I had span in that place but I need to switch to link and here's the trouble - every time I click on .upvotes the page gets refreshed, what I've tried so far:

event.preventDefault() - not working.

upvote: (e) ->
  e.preventDefault()
  // do stuff (ajax)

event.stopPropagation() - not working.

upvote: (e) ->
  e.stopPropagation()
  // do stuff (ajax)

return false - not working.

upvote: (e) ->
  // do stuff (ajax)
  return false

I've also tried all of the above using jQuery in my index.html, but nothing seems to work. What should I do here and what I'm doing wrong? I've checked event.type and it's click so I guess I should be able to avoid redirect somehow?

Excuse me, I'm a rookie when it comes to React.

Thank you!

React events are actually Synthetic Events, not Native Events. As it is written here:

Event delegation: React doesn't actually attach event handlers to the nodes themselves. When React starts up, it starts listening for all events at the top level using a single event listener. When a component is mounted or unmounted, the event handlers are simply added or removed from an internal mapping. When an event occurs, React knows how to dispatch it using this mapping. When there are no event handlers left in the mapping, React's event handlers are simple no-ops.

Try to use Use Event.stopImmediatePropagation:

upvote: (e) ->
  e.stopPropagation();
  e.nativeEvent.stopImmediatePropagation();