JavaScript 中获取对象中的键数
JavaScript 中要获取对象中的键数：
-
调用
Object.keys()方法，将对象作为参数传递。 - 访问结果的长度属性。
-
Object.keys方法返回一个包含对象键的数组。
const obj = {
name: 'Tom',
age: 30,
country: 'Chile',
};
const numOfKeys = Object.keys(obj).length;
console.log(numOfKeys); // 👉️ 3
我们使用 Object.keys 方法获取包含对象键的数组。
const obj = {
name: 'Tom',
age: 30,
country: 'Chile',
};
console.log(Object.keys(obj)); // 👉️ ['name', 'age', 'country']
该方法采用的唯一参数是我们要为其获取键的对象。
当调用一个空对象时，该方法返回一个空数组。
console.log(Object.keys({})); // 👉️ []
最后一步是访问数组的长度属性，以获取对象中键的数量。
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