Unlike whole tutorial, here is rewritten source code available, using Vue.js webpack simple template.
The last direction, how Vue.js components can communicate is child->child, or non parent->child respectively. In simple cases, central event bus fits for this type of communication.
While there is nothing like two-way component communicaton in Vue.js, each data flow must be defined separately.
Because I pass dynamically created string value from parent component to child, props are enough to use.
Components, as the most powerful feature of Vue.js often needs to communicate between each other. Let me show an example of all 3 types of communication: parent -> child, child -> parent, child -> child.