Using Objects for Lookups - antoniojvargas/FreeCodeCamp GitHub Wiki

Using Objects for Lookups

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 a lookup table called lookup. Use it to lookup val and assign the associated string to the result variable.

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

  // Only change code below this line
  var lookup = {
	"alpha":"Adams",
	"bravo": "Boston",
	"charlie": "Chicago",
	"delta": "Denver",
	"echo": "Easy",
	"foxtrot": "Frank"
  };
  result = lookup[val];

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

// Change this value to test
phoneticLookup("charlie");