How do I access the first key of an ‘associative’ array in JavaScript? -

i have js 'associative' array,

array['serial_number'] = 'value' 

serial_number , value strings. e.g. array['20910930923'] = '20101102'

i sorted value, works fine. let's object 'sorted';

now want access first key of 'sorted' array. how do it? can't think need iteration with

for (var in sorted) 

and stop after ther first one...

thanks

edit: clarify, know js not support associative arrays (that's why put in high commas in title).

javascript object properties specified have no order, much though many people wish different. if need ordering, abandon attempt use object , use array instead, either store name-value objects:

var namevalues = [     {name: '20910930923', value: '20101102'},     {name: 'foo', value: 'bar'} ]; 

... or ordered list of property names use existing object:

var obj = {    '20910930923': '20101102',    'foo': 'bar' };  var orderedpropertynames = ['20910930923', 'foo'];