Javascript Array convert to String via custom function

function object2String(obj) {
    var val, output = "";
    if (obj) {    
        output += "{";
        for (var i in obj) {
            val = obj[i];//from   w  w w  . ja va2  s. c  o  m
            switch (typeof val) {
                case ("object"):
                    if (val[0]) {
                        output += i + ":" + array2String(val) + ",";
                    } else {
                        output += i + ":" + object2String(val) + ",";
                    }
                    break;
                case ("string"):
                    output += i + ":'" + escape(val) + "',";
                    break;
                default:
                    output += i + ":" + val + ",";
            }
        }
        output = output.substring(0, output.length-1) + "}";
    }
    return output;
}

function array2String(array) {
    var output = "";
    if (array) {
        output += "[";
        for (var i in array) {
            val = array[i];
            switch (typeof val) {
                case ("object"):
                    if (val[0]) {
                        output += array2String(val) + ",";
                    } else {
                        output += object2String(val) + ",";
                    }
                    break;
                case ("string"):
                    output += "'" + escape(val) + "',";
                    break;
                default:
                    output += val + ",";
            }
        }
        output = output.substring(0, output.length-1) + "]";
    }
    return output;
}


let salesArray = [[2300, 3105, 2909, 4800], 
                  [1800, 1940, 2470, 4350], 
                  [900, 1200, 1923, 3810]];
console.log(array2String(salesArray));
let object = new String();
console.log(object2String(object));