Get value from JSON string using jQuery

I'm trying to parse JSON string with few arrays and some key:value pairs. I'm now able to get values from one array but I want to get values from the other array too. The arrays have same keys but I can't find out how to get data from the second array.

My jQuery script looks like this

$("a").click(function () {
    var page = $(this).text();
    console.log(page);
    $.post("/services/gallery/getimage", {"path[]":[<%=path %>], "page": page}, function(data){
        var length = data.previews.length;
        console.log(length);
        var html = "";
        for(var i = 0; i < length; i++){
            $.each(data.previews[i], function (index, value) {
                html+= "<a href=\""+value+"\"><img src=\""+value+"\" alt=\""+index+"\" /></a>";
                console.log("index: "+index);
                console.log("value: "+value);
                console.log(data.heights[i].index);
            });
        }

        $("#gallery").html(html);
    });
});

I've also tried some modifications of this console.log(data.heights[i].index); but still no usable result.

The console output is

1
15

index: index1
value: /some/path
undefined

index: index2
value: /some/paht
undefined 

and the JSON string looks like this

{
    "previews": [
        {
            "index1": "/some/path"
        },
        {
            "index2": "/some/path"
        }
    ],
    "heights": [
        {
            "index1": "67"
        },
        {
            "index2": "103"
        }
    ]
}

I'll have more arrays with same indexes so it'll be great if it'll be possible to parse it in one for. Thanks for any help

EDIT: Names of attributes are dynamic not static. It can be whatever, not just index1, index2, ...