Example of using javascript to create an associative array of arrays

//Arrays in js can exist as key-value pairs
        var arr = new Array();
        arr["A"] = "boss";
        arr["B"] = "Emp";
        for (var m in arr) {
            document.write(arr[m] + " ");
        }
        var person = new Object();
        person["name"] = "xiaoli";
        person["age"] = "18";
        person["salary"] = "1888.9";
        for (var p in person) {
            document.write(person[p] + "<br>");
        }
        //Does the test use the age property?
        if (typeof person["age"] == "undefined") {
            document.write("no");
        }