javascript - unable to populate 2D array

Question

My instructor tasked us to build a 2D array and populate it with values from our HTML form. He gave us this example to create the array.

var tasks = new Array();
var index = 0;

He then said to insert the values into the two columns using this code.

tasks[index]["Date"] = tempdate;
tasks[index]["Task"] = temptask;

However, something about these two lines is causing the script to break, because when I comment them out the final line of my script returns a value to the correct div. When I uncomment these lines no value is returned. Is there something wrong in my syntax?

This is my complete js file:

var tasks = new Array();
var index = 0;


function addTask() {
    var tempdate = new Date();
    var temptask = document.getElementById("taskinfo").value;
    var td = document.getElementById("taskdate").value;
    tempdate = td + " 00:00";

    tasks[index]["Date"] = tempdate;
    tasks[index]["Task"] = temptask;

    index++

    tasks.sort(function (a, b) { return b.date - a.date });

    var tablecode = "<table class = 'tasktable'>" +
        "<tr>"+
        "<th>Date</th>"+
        "<th>Task</th>"+
        "</tr>";
    for (var i = 0; i < tasks.length; i++) {
        tablecode = tablecode + "<tr>" +
            "<td>" + tasks[i]["Date"].toDateString() + " </td>" +
            "<td>" + tasks[i]["Task"] + " </td>" +
            "</tr>";
    }

    tablecode = tablecode + "</table>";
//I am only returning "temptask" to test with, I will be returning     "tablecode". 
    document.getElementById("bottomright").innerHTML = temptask;

return false;

}

Have you looked at your browser's JavaScript console (F12, in most browsers), it seems likely there's a reported error there that you're overlooking. — David Thomas
– David Thomas, Commented Dec 5, 2015 at 2:47

TAGraves · Accepted Answer · 2015-12-05 02:49:28Z

2

tasks[index] (in the first case, tasks[0]) doesn't yet exist, so you can't give it properties. Try this to create an object and assign it to tasks[index]:

tasks[index] = {
    Date: tempdate,
    Task: temptask
};

in place of

tasks[index]["Date"] = tempdate;
tasks[index]["Task"] = temptask;

Alternatively, you can use

tasks[index] = {};
tasks[index]["Date"] = tempdate;
tasks[index]["Task"] = temptask;

answered Dec 5, 2015 at 2:49

TAGraves

1,4091 gold badge10 silver badges11 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

TAGraves Over a year ago

Glad to help! If this or any answer has solved your question please consider accepting it by clicking the check-mark. This indicates to the wider community that you've found a solution and gives some reputation to both the answerer and yourself. There is no obligation to do this, though. Happy coding!

Collectives™ on Stack Overflow

javascript - unable to populate 2D array

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related