Edit in JSFiddle

<script>
    var aElements = [1,2,3,4,5,6];
    for ( var i=0; i< aElements.length; i++){
        alert(aElements[i]);
    }

    var aElements = [1,2,3,4,5,6];
    for ( var i in aElements){
        alert(aElements[i]);
    }

    var aElements = [1,2,3,4,5,6];
    aElements.forEach (function(iItem){
        alert(iItem);
    });

    var oObject = {};
    oObject.some = 'value 1';
    oObject.property = 'value 2';
    oObject.spokystuff = 'value 3';

    for( sKey in oObject){
        if(oObject.hasOwnProperty(sKey))
            alert(oObject[sKey]);
    }
</script>