How to iterate through property names of Javascript object?

Question

I would like to get the property names from a Javascript 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 object 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 Javascript 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

Use for...in loop:

for (var key in obj) {    console.log(' name=' + key + ' value=' + obj[key]);     // do some more stuff with obj[key] }