How do I access properties of a javascript object if I don't know the names?

You can loop through keys like this:

for (var key in data) {  console.log(key);}

This logs "Name" and "Value".

If you have a more complex object type (not just a plain hash-like object, as in the original question), you'll want to only loop through keys that belong to the object itself, as opposed to keys on the object's prototype:

for (var key in data) {  if (data.hasOwnProperty(key)) {    console.log(key);  }}

As you noted, keys are not guaranteed to be in any particular order. Note how this differs from the following:

for each (var value in data) {  console.log(value);}

This example loops through values, so it would log Property Name and 0. N.B.: The for each syntax is mostly only supported in Firefox, but not in other browsers.

If your target browsers support ES5, or your site includes es5-shim.js (recommended), you can also use Object.keys:

var data = { Name: 'Property Name', Value: '0' };console.log(Object.keys(data)); // => ["Name", "Value"]

and loop with Array.prototype.forEach:

Object.keys(data).forEach(function (key) {  console.log(data[key]);});// => Logs "Property Name", 0

Old versions of JavaScript (< ES5) require using a for..in loop:

for (var key in data) {  if (data.hasOwnProperty(key)) {    // do something with key  }}

ES5 introduces Object.keys and Array#forEach which makes this a little easier:

var data = { foo: 'bar', baz: 'quux' };Object.keys(data); // ['foo', 'baz']Object.keys(data).map(function(key){ return data[key] }) // ['bar', 'quux']Object.keys(data).forEach(function (key) {  // do something with data[key]});

ES2017 introduces Object.values and Object.entries.

Object.values(data) // ['bar', 'quux']Object.entries(data) // [['foo', 'bar'], ['baz', 'quux']]

for(var property in data) {    alert(property);}