JavaScript使用for循环遍历不同长度数组提取匹配国家对象

原代码存在的问题 #

• if判断语句后附带的冗余分号;会直接截断if的逻辑关联，后续代码块会变为无条件执行
• 循环变量i、j未通过let声明，会泄漏为全局变量，造成作用域污染
• 缺少匹配成功后将目标对象存入arr3的核心逻辑

完整可运行代码 #

const arr1 = ["GR", "DE", "AF", "FR"];
const arr2 = [
  { "code": "AF", "code3": "AFG", "name": "Afghanistan" },
  { "code": "GQ", "code3": "GNQ", "name": "Equatorial Guinea" },
  { "code": "FI", "code3": "FIN", "name": "Finland" },
  { "code": "FR", "code3": "FRA", "name": "France" },
  { "code": "GF", "code3": "GUF", "name": "French Guiana" },
  { "code": "PF", "code3": "PYF", "name": "French Polynesia" },
  { "code": "GA", "code3": "GAB", "name": "Gabon" },
  { "code": "GM", "code3": "GMB", "name": "Gambia (the)" },
  { "code": "GE", "code3": "GEO", "name": "Georgia" },
  { "code": "GH", "code3": "GHA", "name": "Ghana" }
];

let arr3 = [];

for (let i = 0; i < arr1.length; i++) {
  for (let j = 0; j < arr2.length; j++) {
    // 移除原if后的多余分号，使用全等匹配避免子串误判
    if (arr2[j].code === arr1[i]) {
      arr3.push(arr2[j]);
    }
  }
}

运行结果 #

执行后arr3的值完全符合预期：

[
  { code: 'AF', code3: 'AFG', name: 'Afghanistan' },
  { code: 'FR', code3: 'FRA', name: 'France' }
]

拓展说明：如果需要避免重复存入相同code的对象，可在push前增加判断：if (!arr3.some(item => item.code === arr2[j].code)) arr3.push(arr2[j])，适合arr2存在重复数据的场景。

内容的提问来源于stack exchange，提问作者mat1