javascript - 检查对象的空元素

Question

http GET 方法的响应如下所示:

{
  id:1,
  name:"John",
  subjects:[],
  totalMarks:458
}

在前端我想检查subjects 属性是否为空。我尝试过这种方法但没有用

var newObj= {
    id:1,
    name:"John",
    subjects:[],
    totalMarks:458
}

if (newObj.subjects == null) {
  alert("Empty subjects");
}

Answer 1

newObj.subjects 是Array，所以你需要这样检查它

if(Array.isArray(newObj.subjects) && !newObj.subjects.length) {
   alert("Empty subjects");
}