Function is called too many times and retains old variable values

Function is called too many times and retains old variable values

I currently have a table that is updated every time a user presses a
button (handled using Backbone events).
Here is the event that is fired every time the button is pressed:
add: function(ev) {
if($(ev.target).data("card-id")) {
this.card_array.push($(ev.target).data("card-id"));
current_deck.push($(ev.target).data("card-id"));
updateCurrentDeckTable();
} else {
alert("Couldn't add the card. Please wait a few seconds
before trying again.");
}
console.log(this.card_array);
console.log(current_deck);
}
updateCurrentDeckTable is defined as so:
function updateCurrentDeckTable() {
console.log(current_deck);
var content = "";
$.each(current_deck, function(i, cardId) {
console.log("Index: "+i+" || Card ID: "+cardId);
var M_Card = Parse.Object.extend("Card");
var M_CardQuery = new Parse.Query(M_Card);
M_CardQuery.get(cardId, {
success: function(m_card) {
console.log("Got "+m_card.get("cardTitle"));
content += "<tr>";
content += "<td>"+m_card.get("objectiveNumber")+"</td>";
content += "<td>"+m_card.get("cardTitle")+"</td>";
if (m_card.get("cardAffiliation") == null) {
content += "<td>-</td>";
} else {
content +=
"<td>"+m_card.get("cardAffiliation")+"</td>";
}
content += "<td><a>Details</a></td>";
content += "</tr>";
console.log("Content: "+content);
$('#deck-table tbody').append(content);
},
error: function() {
alert("Error.");
}
});
});
}
Now, the first time the user presses the button, everything works just
fine. However, on the second press, more than one row is added to the
table. Further, the content variable seems to keep it's old values.
Shouldn't it reset to "" every time the function is called?
Does anyone have any idea what's happening? If you need more information,
please ask.