[
    folder1/folder2/file1.txt,
    folder1/folder2/folder3/file1.txt,
    folder1/folder2/file2.txt
]

[
    {
        "name": "file1.txt",
        "isDirectory": false
    }
    {
        "name": "folder3",
        "isDirectory": true
    }
    {
        "name": "file2.txt",
        "isDirectory": false
    }
]

var paths = [
    "folder1/folder2/file.txt",
    "folder1/folder2/folder3/file2.txt",
    "folder1/folder2/file2.txt",
    "folder1/folder3/file3.txt",
]

function getFilesInDir(path) {
    var files = [];
    var pathLength = path.split("/").length;
    paths.forEach(pth => {
        var pthSplit = pth.split("/");
        var length = pthSplit.length;
        for(var i = 0; i < length; i++) {
            var element = pthSplit.pop();
            if(pthSplit.join("/") == path) {
                var isDirectory = (i != 0);
                var file = {
                    name: element,
                    isDirectory
                };
                if(files.filter(fl => {
                    return JSON.stringify(fl) == JSON.stringify(file);
                }).length == 0) files.push(file);
            }
        }
    });
    return(files);
}

console.log(getFilesInDir("folder1/folder2"));