If `props` and `data` are both present in the component declaration, `props` will not been initialised with default value.

[federicodionisi]

Here you can fine two examples, one with and one without data property on the $parent component:

https://jsfiddle.net/wLx0j53o/3/

https://jsfiddle.net/wLx0j53o/4/

When data is present, props seems to be initialised only if declared in the template.