The for...in statement is used to iterate a declared variable over every property in a specified object. The code in the body of the for ... in loop is executed once for each property. The variable argument can be a named variable, an array element, or a property of the object.

This example simply displays the names of all the properties of the 'drink' object:

Code:
var i;
for(i in drink)
   document.write(i + "<BR>");

You can also have a specified variable iterate over the values of an object's properties by placing it between square brackets after the object name. Expanding on the previous example, the following code displays both the name of each property in the 'drink' object and its value:

Code:
var i;
for(i in drink)
   document.write(i + ":   " + drink[i] + "<BR>");