FindPath.js

var items = 
{"itemList": {"items": [
    {"id": "item1"},
    {"id": "item2","label": "Item 2"},
    {"id": "item3"},
    {"id": "item4"},
    {"id": "item5"},
    {"id": "subItem1",
        "subItems": [
            {"id": "subItem1Item1","label": "SubItem 1"},
            {"id": "subItem1Item2","label": "SubItem 2"},
            {"id": "subItem1Item3","label": "SubItem 3"}
        ]
    },
    {"id": "item6"},
    {"id": "item7","label": "Item 7"},
    {"id": "subItem2",
        "subItems": {"id": "item1","label": "SubItem 2 item1"}
    }
]}}

/** Check if the string is a number or not. 
  * Returns true if it's a number, false otherwise */
function isNumeric(num){
    return !isNaN(num);
}

/** Returns the full path given a value. 
  * @param: data is the JSON file
            value is the value that we need to find
            path is the previous path */
function findPath(data, value, path)
{
    path = path || "";
    var finalpath = [];
    
    // Check if data is valid
    if(typeof(data) != "object" || Object.keys(data).length == 0) 
        return ( "input is not the correct type or object is empty" );

    for(var obj in data)  { 
        if (data[obj] == value)
            return ( path + "/" + obj);
            
        else if (typeof data[obj] == "object") {
            var temp;
            if ( isNumeric(obj) )
                temp = findPath(data[obj], value,  path + "[" + obj + "]");
            else 
                temp = findPath(data[obj], value,  path + "/" + obj);
                
            if (temp.length) {
                finalpath.push(temp);
            }
        }
    }
        
    return finalpath.toString();
}

var text = findPath(items, "item2");
console.log(text)