67

I'm trying to count the length of the JSON array element. I know to count the length of array using json.array.length. That is need to find that how many items in every index.

If my array is:

{ "shareInfo": [{ "id": "1", "a": "sss", "b": "sss", "question": "whi?" }, { "id": "2", "a": "sss", "b": "sss", "question": "whi?" }, { "id": "3", "a": "sss", "b": "sss", "question": "whi?" }, { "id": "4", "a": "sss", "b": "sss", "question": "whi?" } ] }

Then I need to find the length of {"id":"1","a":"sss","b":"sss","question":"whi?"}. In this there have four items. I tried this with data.shareInfo[i].length. But it produces error.

Please anyone tell me how to find the length.... Thanks....

Improve this question
2
  • Is this in JSON, or an actual array? Commented Mar 4, 2013 at 19:10
  • there's no such thing as a json array. there's json STRINGS. if it's an array, then it's native javascript and not "json". Commented Mar 4, 2013 at 19:10

4 Answers 4

Reset to default
111

Before going to answer read this Documentation once. Then you clearly understand the answer.

Try this It may work for you.

Object.keys(data.shareInfo[i]).length
Improve this answer
Sign up to request clarification or add additional context in comments.

1 Comment

it is only supported for IE9+ ...
19

First if the object you're dealing with is a string then you need to parse it then figure out the length of the keys : 

obj = JSON.parse(jsonString); shareInfoLen = Object.keys(obj.shareInfo[0]).length;
Improve this answer

2 Comments

It produces the error shareInfo is not defined. But I have the array called shareInfo
@ahjmorton your answer is correct for javascript arrays. If it is json array then it must be Object.keys(data.shareInfo[i]).length
1

First, there is no such thing as a JSON object. JSON is a string format that can be used as a representation of a Javascript object literal.

Since JSON is a string, Javascript will treat it like a string, and not like an object (or array or whatever you are trying to use it as.)

Here is a good JSON reference to clarify this difference:

http://benalman.com/news/2010/03/theres-no-such-thing-as-a-json/

So if you need accomplish the task mentioned in your question, you must convert the JSON string to an object or deal with it as a string, and not as a JSON array. There are several libraries to accomplish this. Look at http://www.json.org/js.html for a reference.

Improve this answer

1 Comment

You are right. But we can pass the values from server by using JSONarray. For archive this we need to create JSONarray ->>then toJsonTree Then we can convert the object to String. In client side we will receive result as above .( as array in the question).
0

I think you should try 

data = {"shareInfo":[{"id":"1","a":"sss","b":"sss","question":"whi?"}, {"id":"2","a":"sss","b":"sss","question":"whi?"}, {"id":"3","a":"sss","b":"sss","question":"whi?"}, {"id":"4","a":"sss","b":"sss","question":"whi?"}]}; ShareInfoLength = data.shareInfo.length; alert(ShareInfoLength); for(var i=0; i<ShareInfoLength; i++) { alert(Object.keys(data.shareInfo[i]).length); }
Improve this answer

Comments