How to get the length of a json returned data and run a for loop

Question

I have this ajax call which its result is in a json format

$.ajax({
    url: link,
    dataType: "json",
    success: function(data){
        console.log(data); //C.L-1
        console.log(data.length); //C.L-2
    }
})

And here is the result

$users_arr = array();
//After a successful query from my database
While($sql = mysqli_fetch_array($query)){
    $user_id = $sql['id'];
    $user_age = $sql['age'];
    $user_name = $sql['name'];
    $users_arr[$user_id] = $user_id.','.$user_name.','.$user_age;
}
echo json_encode($users_arr);

Now the C.L-1 returns true but the C.L-2 returns undefined. I thought the data returned is an array on it's own so I want to run a for loop for each user like this

for(var i = 0; data.length > i; i++){
    eachUser = data[i];
    userInfo = eachUser.split(',');
    userId = userInfo[0]; // and so on for the other info
    $('div#age'+userId).html(userAge);
}

But the problem is that the data.length returns undefined which prevents me for running my for loop. Please any better help?

Edit here are some data from C.L-1

Object {8: "8,debbie,23", 3: "3,doggie,20", 7: "7,dini,22"}

What `C.L.-1` and ``C.L.-2`` means? Also, where are you doing the loop? Inside or outside AJAX success? — Ionut Necula, Nov 10 '16 at 12:42
console.log(data) returns true? What exactly is in the console.log? — epascarello, Nov 10 '16 at 12:44
I guess **C**onsole **.L**og. or may be **C**onsole **L**ine — Rajesh, Nov 10 '16 at 12:44
@lonut C.L means console.log as you can see I commented them out. And my loop is inside my AJAX success — doggie brezy, Nov 10 '16 at 12:47
@doggiebrezy, you say that `C.L-1` returns `true`. Is that actually true, or it returns some data? If it returns an object, can you please post that object in your question? — Ionut Necula, Nov 10 '16 at 12:49
C.L-1 outputted and array with the user_id as the keys and the user_info as the values or each user which is what I need — doggie brezy, Nov 10 '16 at 12:49
@doggiebrezy, can you post the JSON in your question please? — Ionut Necula, Nov 10 '16 at 12:53

Ionut Necula · Accepted Answer · 2016-11-10T13:40:48.467

2

With a simple for ... in loop:

var obj = {
  7: "8,debbie,23",
  8: "3,doggie,20",
  9: "7,dini,22"
};

for(var x in obj){
  console.log(obj[x]);
}

An alternative to the for in loop can be:

var obj = {
  7: "8,debbie,23",
  8: "3,doggie,20",
  9: "7,dini,22"
};

Object.keys(obj).forEach(function(key) {
    console.log(key, obj[key]);
});

Important is to know that you can use the next two options only when the keys start from 0.

You can count the elements in your object like this:

var obj = {
  0: "8,debbie,23",
  1: "3,doggie,20",
  2: "7,dini,22"
};
var wrong_count = obj.length; //this will return undefined
var correct_length = Object.keys(obj).length; //this will return 3
console.log(wrong_count);
console.log(correct_length);

for(var i = 0; i < correct_length; i++){
  console.log(obj[i]);
}

For more info about Object.keys() you can refer to this link.

Another alternative to that would be to use a for in loop:

var obj = {
  0: "8,debbie,23",
  1: "3,doggie,20",
  2: "7,dini,22"
};

var another_count = 0;
for(var x in obj){
 another_count++;
}
console.log(another_count);

for(var i = 0; i < another_count; i++){
  console.log(obj[i]);
}

edited Nov 10 '16 at 13:40

answered Nov 10 '16 at 12:56

Ionut Necula

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but what about my for loop? I tried this `for(var i = 0; count > i; i++){ console.log(data[i]); }` but I get undefined – doggie brezy Nov 10 '16 at 13:04
That means that your object keys does not match with the loop indexes. Otherwise it should work. See my updated answer. Observe the keys numbers. – Ionut Necula Nov 10 '16 at 13:07
how do I get the values of each key in the object? – doggie brezy Nov 10 '16 at 13:10
It's already happening that in my answer. Check carefully. – Ionut Necula Nov 10 '16 at 13:11
I created the keys myself, so the keys isnt `0,1,2,3...` – doggie brezy Nov 10 '16 at 13:11
You can use a `for in` loop for that. And you wouldn't even need the object length anymore. – Ionut Necula Nov 10 '16 at 13:18
@LSerni, it was the first answer that was given. It wasn't all clear until discussed it with the OP, after that the answer was improved gradually. – Ionut Necula Nov 10 '16 at 13:28
You might want to add the jslint check described here: http://stackoverflow.com/a/4166584/1428679 . Even so, very goo work with the snippets; +1 for that too :-) – LSerni Nov 10 '16 at 13:44

How to get the length of a json returned data and run a for loop

1 Answers1