JavaScript：如何检查对象是否包含元素或者为空对象？

let obj1 = {}
let obj2 = { name: 'Tom' }

console.log(JSON.stringify(obj1)); 
// {}

console.log(JSON.stringify(obj2));
// {"name":"Tom"}

let obj1 = {}
let obj2 = { name: 'Tom' }

console.log(Object.keys(obj1));
// []

console.log(Object.keys(obj2));
// [ 'name' ]

let obj1 = {}
let obj2 = { name: 'Tom' }

function isEmpty(obj) {
  for (var key in obj) {
    return false
  }

  return true
}

console.log(isEmpty(obj1))
// true

console.log(isEmpty(obj2))
// false