如何获得JSON数组的长度？(How to get the length of JSON array?)

 我有一个与以下类型的响应json网址 
 
[
  {
    "gender": "Female",
    "age": 7,
    "class": 2,
    "subject": [
      "",
      "",
      ""
    ]
  },
  {
    "gender": "Female",
    "age": 8,
    "class": 3,
    "subject": [
      "ab",
      "cd",
      "ef"
    ]
  },
  ...
]
 
 我想找到这个数组的长度 
 
 所以在我使用的角度应用程序 
 
export class CustomComponent implements OnInit {

  length: number;
  constructor() { 
    this.length = Object.keys('www.url...').length;
    console.log(length);
  }
 
 在.html中我有<p>{{ length }}</p> 
 
 我得到61，而实际的长度是44，但另一方面控制台显示0。 
 
 我哪里错了？ 
 
 任何形式的帮助将不胜感激。 谢谢。 

I have a json url with a response of the following kind
 
[
  {
    "gender": "Female",
    "age": 7,
    "class": 2,
    "subject": [
      "",
      "",
      ""
    ]
  },
  {
    "gender": "Female",
    "age": 8,
    "class": 3,
    "subject": [
      "ab",
      "cd",
      "ef"
    ]
  },
  ...
]
 
I want to find the length of this array
 
so in the angular app I am using
 
export class CustomComponent implements OnInit {

  length: number;
  constructor() { 
    this.length = Object.keys('www.url...').length;
    console.log(length);
  }
 
in .html I have <p>{{ length }}</p>
 
I am getting 61 whereas the actual length is 44, but the console on the other hand is showing 0.
 
Where am I going wrong?
 
Any kind of help would be greatly appreciated. Thanks.

原文：https://stackoverflow.com/questions/49105886