Javascript 对象 - 检查并循环遍历对象中的数组

Question

我试图遍历一个对象文字，如果一个属性是一个数组，我也想遍历它。 这个对象的朋友属性是一个数组，我将如何测试它是否可迭代，然后循环遍历它？

提前致谢，

  firstName: 'Jonas',
  lastName: 'Schmedtmann',
  age: 2037 - 1991,
  job: 'teacher',
  friends: ['Michael', 'Peter', 'Steven'],
};
const myObj = Object.entries(jonas);
for (const [key, val] of myObj) {
   //Some conditional statement here testing for an interable
   //Then loop through it to the console.
  console.log(key, val);
}

Answer 1

所有数组都是 Javascript 中Array类的实例，因此您可以使用var instanceof Array返回一个布尔值来检查元素是否为数组，然后根据需要对其进行迭代

 const obj = { firstName: 'Jonas', lastName: 'Schmedtmann', age: 2037 - 1991, job: 'teacher', friends: ['Michael', 'Peter', 'Steven'], }; const myObj = Object.entries(obj); for (const [key, val] of myObj) { //Some conditional statement here testing for an interable //Then loop through it to the console. if (val instanceof Array) { console.log('element is an array, printing now') print(val); } else console.log(key, val); } function print(ar) { ar.forEach(x => console.log(x)); }