In CoffeeScript it might look something like this:

element = type: 'div' props: className: 'container', children: [ type: 'span', props: className: 'foo' type: CustomClass, props: className: 'bar' ]

(This doesn't fully work in 0.12 because we also have some extra properties on there but that's the direction we're going.)

0.12 is just adding React.createFactory. 0.13 will optionally replace React.createClass.

We do this so that there's a seamless upgrade path. We have to remove the warnings to fix the classes.

I guessed that indentation:

    element =
      type: 'div'
      props: className: 'container'
      children: [
          type: 'span'
          props: className: 'foo'
      ,
          type: CustomClass
          props: className: 'bar' 
      ]

Thanks for the answers.

I will say that I do really like the syntax of coffeescript as is though,

  div className: 'container',
    span className: 'foo'
    CustomClass classname: 'bar'

It reminds me a lot of slim and reads nicely.