This pattern is a dynamic and extensible alternative to multiple if-else blocks, or a switch statement

lookup-map-example.js

const logMessage = (message) => console.log(Date.now(), message)

const responses = [
  {
    input: "test-one",
    answer: "One",
  },
  {
    input: "test-two",
    helper: (input, callback) => {
      callback("Two helper")
    },
  },
]

const matchResponses = (input, callback) => {
  const results = responses.filter((response) => {
    return response.input == input
  })
  results.forEach((result) => {
    if (typeof result.helper == "function") result.helper(input, callback)
    else if (typeof callback == "function") callback(result.answer)
  })
}


["test", "test-one", "test-two"].forEach((input) =>
  matchResponses(input, logMessage)
)

See more about why we use the callback parameter on matchResponses in my related gist