freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/using-objects-for-lookups.md

id, title, challengeType, videoUrl, forumTopicId

id	title	challengeType	videoUrl	forumTopicId
56533eb9ac21ba0edf2244ca	Using Objects for Lookups	1	https://scrimba.com/c/cdBk8sM	18373

--description--

Objects can be thought of as a key/value storage, like a dictionary. If you have tabular data, you can use an object to "lookup" values rather than a switch statement or an if/else chain. This is most useful when you know that your input data is limited to a certain range.

Here is an example of a simple reverse alphabet lookup:

var alpha = {
  1:"Z",
  2:"Y",
  3:"X",
  4:"W",
  ...
  24:"C",
  25:"B",
  26:"A"
};
alpha[2]; // "Y"
alpha[24]; // "C"

var value = 2;
alpha[value]; // "Y"

--instructions--

Convert the switch statement into an object called lookup. Use it to look up val and assign the associated string to the result variable.

--hints--

phoneticLookup("alpha") should equal "Adams"

assert(phoneticLookup('alpha') === 'Adams');

phoneticLookup("bravo") should equal "Boston"

assert(phoneticLookup('bravo') === 'Boston');

phoneticLookup("charlie") should equal "Chicago"

assert(phoneticLookup('charlie') === 'Chicago');

phoneticLookup("delta") should equal "Denver"

assert(phoneticLookup('delta') === 'Denver');

phoneticLookup("echo") should equal "Easy"

assert(phoneticLookup('echo') === 'Easy');

phoneticLookup("foxtrot") should equal "Frank"

assert(phoneticLookup('foxtrot') === 'Frank');

phoneticLookup("") should equal undefined

assert(typeof phoneticLookup('') === 'undefined');

You should not modify the return statement

assert(code.match(/return\sresult;/));

You should not use case, switch, or if statements

assert(
  !/case|switch|if/g.test(code.replace(/([/]{2}.*)|([/][*][^/*]*[*][/])/g, ''))
);

--seed--

--seed-contents--

// Setup
function phoneticLookup(val) {
  var result = "";

  // Only change code below this line
  switch(val) {
    case "alpha":
      result = "Adams";
      break;
    case "bravo":
      result = "Boston";
      break;
    case "charlie":
      result = "Chicago";
      break;
    case "delta":
      result = "Denver";
      break;
    case "echo":
      result = "Easy";
      break;
    case "foxtrot":
      result = "Frank";
  }

  // Only change code above this line
  return result;
}

phoneticLookup("charlie");

--solutions--

function phoneticLookup(val) {
  var result = "";

  var lookup = {
    alpha: "Adams",
    bravo: "Boston",
    charlie: "Chicago",
    delta: "Denver",
    echo: "Easy",
    foxtrot: "Frank"
  };

  result = lookup[val];

  return result;
}