JSON.stringify serializes to [[]]

Question

If I create a JavaScript object like:

var lst = [];
var row = [];
row.Col1 = \'val1\';
row.Col2 = \'val2\'; 
lst.push(row);

And then convert it

Answer 1

You want row to be a dictionary, not a vector. Define it like this:

var row = {};

Answer 2

Because row is an array, not an object. Change it to:

var row = {};  

This creates an object literal. Your code will then result in an array of objects (containing a single object):

[{"Col1":"val1","Col2":"val2"}]

Update

To see what really happens, you can look at json2.js on GitHub. This is a (heavily reduced) snippet from the str function (called by JSON.stringify):

if (Object.prototype.toString.apply(value) === '[object Array]') {
    //...
    length = value.length;
    for (i = 0; i < length; i += 1) {
        partial[i] = str(i, value) || 'null';
    }
    //...
}
//...
for (k in value) {
    if (Object.prototype.hasOwnProperty.call(value, k)) {
        //...
    }
    //...
}
//...

Notice that arrays are iterated over with a normal for loop, which only enumerates the array elements. Objects are iterated with a for...in loop, with a hasOwnProperty test to make sure the proeprty actually belongs to this object.

Answer 3

You use your inner array like an object, so make it an object instead of an array.

var lst = [];
var row = {};
row.Col1 = 'val1';
row.Col2 = 'val2'; 
lst.push(row);

or use it as an array

var lst = [];
var row = {};
row.push( 'val1' );
row.push( 'val2' );
lst.push(row);

Answer 4

Since an array is a datatype in JSON, actual instances of Array are stringified differently than other object types.

If a JavaScript Array instance got stringified with its non-numeric keys intact, it couldn't be represented by the [ ... ] JSON array syntax.

For instance, [ "Col1": "val1"] would be invalid, because JSON arrays can't have explicit keys.
{"Col1": "val1"} would be valid - but it's not an array.

And you certainly can't mix'n'match and get { "Col1": "val1", 1, 2, 3 ] or something.

By the way, this works fine:

var lst = [];
var row = {};
row.Col1 = 'val1';
row.Col2 = 'val2'; 
lst.push(row);
alert(JSON.stringify(lst));​