graph-routing.js

const routeMap = [
  { from: "A", to: "B", cost: 1 },
  { from: "A", to: "C", cost: 4 },
  { from: "A", to: "D", cost: 10 },
  { from: "B", to: "E", cost: 3 },
  { from: "C", to: "D", cost: 4 },
  { from: "C", to: "F", cost: 2 },
  { from: "D", to: "E", cost: 1 },
  { from: "E", to: "B", cost: 3 },
  { from: "E", to: "A", cost: 2 },
  { from: "F", to: "D", cost: 1 }
]

function calculator(input) {
  if (!input) throw "input is required."

  const routes = input.split("-")

  if (routes.length < 2)
    throw 'route must have destination as follow "A-C", "D-F", "A-F-D"'

  let accumulatedCosts = 0

  routes.reduce((prev, current) => {
    const route = routeMap.find(
      route => route.from === prev.toUpperCase() && route.to === current.toUpperCase()
    )

    if (!route) throw "route not found"

    accumulatedCosts += route.cost

    return current
  })

  return accumulatedCosts
}

console.log("result: A-B-E =>", calculator("A-B-E"))
console.log("result: A-D =>", calculator("A-D"))
console.log("result: E-A-C-F =>", calculator("E-A-C-F"))

try {
  console.log("result: A-D-F =>", calculator("A-D-F"))
} catch (e) {
  console.log("result: A-D-F => no such route")
}