Parsing an json array

Ok - im sure this is pretty basic - but I cant wrap my head around it.
(Im new to js)

Im hitting an outside php script and returning a json string to javascript.
(also - what is the proper term - is it a json string or json array?)
But basically it looks like this when JS gets it from php :

{"account_id":"123","account_type_id":"10","account_role_id":"40","account_username":"test123","account_password":"passwd","account_email":"test@test.com"}

Once I get it back into javascript - I want to just loop thru it and echo out each key and value.
(I dont know what they key name are - they can change each time)
In php id do something like this :
foreach ($array as $key=>$value)
{
echo "$key ---> $value";
}

How do I do the same thing for a json string?

Thanks

 

for (var i in json_array)
{
	alert(i); // Key
	alert(json_array[i]); // Value
}

Code (javascript):

 

perfect - thanks
I knew it was easy

 

It's actually an object containing name:value pairs in the form of strings.