Get Property Names In JSON Objects

Question

I would like to get the property names from a JSON object to build a table dynamically

example:

var obj = { 'fname': 'joe', 'lname': 'smith', 'number': '34' };

for (var i = 0; i < obj.properties.length; i++) {
    alert(' name=' + obj.properties[i].name 
        + ' value=' + obj.properties[i].value);
}

would alert

name=fname value=joe

name=lname value=smith

name=number value=34

---

then I could build a table using json like this

var obj = { 'players': [ 
     { 'fname': 'joe', 'lname': 'smith', 'number': '34'} , 
     { 'fname': 'jim', 'lname': 'Hoff', 'number': '12'} , 
     { 'fname': 'jack', 'lname': 'jones', 'number': '84'}   
] };

to produce...

fname lname number

joe smith 34

jim Hoff 12

jack jones 84

UPDATE

thanks to the answer I have produced a table from the json objects using the property names from the first object in the list for the headers

    function renderData() {
        var obj = { 'players': [
            { 'fname': 'joe', 'lname': 'smith', 'number': '34' },
            { 'fname': 'jim', 'lname': 'jones', 'number': '12' },
            { 'fname': 'jack', 'lname': 'Hoff', 'number': '84' } 
            ] };

        var cols = GetHeaders(obj); 

        $('#Output').html(CreateTable(obj, cols));
    }


    function CreateTable(obj, cols) {
        var table = $('<table></table>');
        var th = $('<tr></tr>');
        for (var i = 0; i < cols.length; i++) {
            th.append('<th>' + cols[i] + '</th>');
        }
        table.append(th);

        for (var j = 0; j < obj.players.length; j++) {
            var player = obj.players[j];
            var tr = $('<tr></tr>');
            for (var k = 0; k < cols.length; k++) {
                var columnName = cols[k];
                tr.append('<td>' + player[columnName] + '</td>');
            }
            table.append(tr);
        }
        return table;
    }



    function GetHeaders(obj) {
        var cols = new Array();
        var p = obj.players[0];
        for (var key in p) {
            //alert(' name=' + key + ' value=' + p[key]);
            cols.push(key);
        }
        return cols;
    }

Answer 1

for (var key in obj) {
   alert(' name=' + key + ' value=' + obj[key]);

   // do some more stuff with obj[key]
}