How does for in js implement traversal in foreach

Foreach is not a keyword in js, but it can be traversed using var v in array. But it's important to note that,
You get the key instead of the value. See the examples:

 
<script type="text/javascript"> 

//Regular array
var intArray = new Array(); 
intArray[0] = " The first one "; 
intArray[1] = " The second "; 

for(var i = 0; i<intArray.length;i++) 
{ 
alert(intArray[i]); //The first one, the second one
} 
//You get a subscript (like the key of a dictionary)
for(var key in intArray) 
{ 
alert(key); // 0,1 
} 


//The dictionary array
var dicArray = new Array(); 
dicArray["f"] = " The first one "; 
dicArray["s"] = " The second "; 

//Unable to get to
for(var i = 0; i<dicArray.length;i++) 
{ 
alert(dicArray[i]); 
} 

//I get a subscript
for(var key in dicArray) 
{ 
alert(key); // f,s 
} 
</script>