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

id, title, challengeType, videoUrl, forumTopicId, dashedName

id	title	challengeType	videoUrl	forumTopicId	dashedName
56533eb9ac21ba0edf2244ca	使用對象進行查找	1	https://scrimba.com/c/cdBk8sM	18373	using-objects-for-lookups

--description--

對象和字典一樣，可以用來存儲鍵/值對。 如果數據是扁平的，你可以用對象來查找你想要的值，而不是鏈式使用 switch 或 if/else 語句。 當你知道你的輸入數據在某個範圍時，這種查找方式極爲有效。

這是一個文章對象的示例：

const article = {
  "title": "How to create objects in JavaScript",
  "link": "https://www.freecodecamp.org/news/a-complete-guide-to-creating-objects-in-javascript-b0e2450655e8/",
  "author": "Kaashan Hussain",
  "language": "JavaScript",
  "tags": "TECHNOLOGY",
  "createdAt": "NOVEMBER 28, 2018"
};

const articleAuthor = article["author"];
const articleLink = article["link"];

const value = "title";
const valueLookup = article[value];

articleAuthor 是字符串 Kaashan Hussain，articleLink 是字符串 https://www.freecodecamp.org/news/a-complete-guide-to-creating-objects-in-javascript-b0e2450655e8/，valueLookup 是字符串 How to create objects in JavaScript。

--instructions--

把 switch 語句轉化爲對象 lookup 調用。 使用它來查找 val 屬性的值，並賦值給 result 變量。

--hints--

phoneticLookup("alpha") 應該等於 Adams

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

phoneticLookup("bravo") 應該等於 Boston

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

phoneticLookup("charlie") 應該等於 Chicago

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

phoneticLookup("delta") 應該等於 Denver

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

phoneticLookup("echo") 應該等於 Easy

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

phoneticLookup("foxtrot") 應該等於字符串 Frank

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

phoneticLookup("") 應該等於 undefined。

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

請不要修改 return 語句

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

請不要使用 case、switch、if 語句

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

--seed--

--seed-contents--

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

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

  result = lookup[val];

  return result;
}