Js Map List Traversal

Map (exMap: {"name": "abc", "sex", 'male '}):

Traverse the map without knowing the key:

I have said this method on the Internet:

[Javascript]
For (var key in exMap ){
Console. write ("key:" + key + "; value:" + exMap [key]); // the key is undefined. but, some times I use it is good. so why is it caused? Can you help me? .
}

For (var key in exMap ){
Console. write ("key:" + key + "; value:" + exMap [key]); // the key is undefined. but, some times I use it is good. so why is it caused? Can you help me? .
} Another method (Good ):

[Javascript]
$. Each (exMap, function (key, value ){
Console. write ("key:" + key + "; value:" + value );
});

$. Each (exMap, function (key, value ){
Console. write ("key:" + key + "; value:" + value );
});

If you know the key, traversing the map is naturally the same as accessing the array.

List access is simple:
[Javascript]
For (var I = 0; I <list. length; I ++ ){
Value = list [I]
}

For (var I = 0; I <list. length; I ++ ){
Value = list [I]
}
Reference (jquery filters the grep, each, inArray, and map of arrays and traverses json objects ):