reveal in explorer js

Maybe I understood what you want

var the_name = activeDocument.name;

var files = activeDocument.path.getFiles();

files.sort(sort_func);

function sort_func(a, b) 
    {
    // Sorting will be alphabetical. 
    // It may differ from the one set in the explorer, especially for names with numbers.
    // For exact matching of sorting, you need to write another sorting function. 
    // Google will help you. )

    if (a > b) return 1;
    else if (a < b) return -1;
    else return 0;
    }

// here you can close activeDocument
// activeDocument.close(SaveOptions.DONOTSAVECHANGES);


for (var i = 0; i < files.length; i++)
    {
    if (files[i].name.toLowerCase() == the_name.toLowerCase())
        {
        if (i != files.length-1) 
            {
            open(files[i+1]);
            break;
            }    
        }
    }

if (i == files.length) alert("it was the last file");