Javascript 中的 Array.length 不起作用

Question

I tried to get length from array but it worked abnormally. Here is my object,

var user = {
  "username":"testuser update",
  "email":"user001@mail.co.th",
  "name":"user001",
  "ownAccount":"[
    {"id":2,"name":"Demo Account2"},
    {"id":1,"name":"Demo Account"}
  ]"
}

I want to get length of ownAccount, I tested by logging it,

console.log(user.ownAccount.length);

It showed 64 !!!, it didn't show 2 . I didn't understand what I did wrong.

Thanks for help.

Answer 1

Its not an array you need to parse it first to get as an array :

var ownAc=JSON.parse(user.ownAccount)
console.log(ownAc.length);

Answer 2

Use the simple method Object.keys(obj) with the reference of https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

In your case the answer is Object.keys(user.ownAccount).length

 var user = { "username": "testuser update", "email": "user001@mail.co.th", "name": "user001", "ownAccount": [{ "id": 2, "name": "Demo Account2" }, { "id": 1, "name": "Demo Account" } ] }; console.log(Object.keys(user.ownAccount).length);

Answer 3

The array is defined as a string , you should remove the double quotes. In other terms, replace "[ with [ and ]" with ] .

Answer 4

Problem for Double quotes

"[ {"id":2,"name":"Demo Account2"}, {"id":1,"name":"Demo Account"} ]"

Solution to remove the double quotes (if your array is your manual format)

try this code

  [
    {"id":2,"name":"Demo Account2"},
    {"id":1,"name":"Demo Account"}
  ]

Solution (to if this array coming from any third parties)

try this code with your json data

var user = {
  "username":"testuser update",
  "email":"user001@mail.co.th",
  "name":"user001",
  "ownAccount":"[
    {"id":2,"name":"Demo Account2"},
    {"id":1,"name":"Demo Account"}
  ]"
}

user.ownAccount = JSON.parse(user.ownAccount)
console.log(user.ownAccount.length);

Answer 5

Try this:

var user = {
  username:"testuser update",
  email:"user001@mail.co.th",
  name:"user001",
  ownAccount:[
    {id:2,name:"Demo Account2"},
    {id:1,name:"Demo Account"}
  ]
}