"Unexpected token o" when using $.parseJSON

Question

The following ajax call gives the following result:

    $.ajax({
        type: "POST",
        url:  //**My full URL goes here**,
        data: {sources: sources},
        dataType: "json",
        success: function(data) {
            alert(data);
            alert(data.length);
            for (var i = 0; i < data.length; i++)
            {
                alert(data[i]);
            }
        }
    });

Result:

data:
[objject object],[objject object],[objject object]

length:
3

in loop:
[objject object]
[objject object]
[objject object]

and the following code , in which I just added:

var data = $.parseJSON(data);
$.ajax({
    type: "POST",
    url:  //**My full URL goes here**,
    data: {sources: sources},
    dataType: "json",
    success: function(data) {
        var data = $.parseJSON(data);
        alert(data);
        alert(data.length);
        for (var i = 0; i < data.length; i++)
        {
            alert(data[i]);
        }
    }
});

The above code gives me the following error:

Uncaught Syntax Error: Unexpected token o

Why is that? Am I doing something wrong? How can I fix it?

Answer 1

The data is already a parsed object since you are passing dataType: 'json', so there is no need to parse it again.

Again to debug and inspect the value of data, use console logging instead of alert(), like console.log(data)

Answer 2

Stop use alert to debug, use console.log instead.

success: function(data) {
  // in the browser console, you will see the data structure.
  // then do what you want
  console.log(data);
  // ...