src/Router.js
function preventTransition(current, newState, diff) {
    if (!current) return false

    return (newState.state == current.state) && (Object.keys(diff.all).length == 0)
  }
function preventTransition(current, newState, diff) {
    if (!current) return false

    return (newState.state == current.state) && (Object.keys(diff.all).length == 0)
  }
/*
Return whether the passed state is the same as the current one
in which case the router can ignore the change.