Question

I am using jQuery 1.7.1 (but that’s probably irrelevant).

I have several JavaScript arrays that are populated in several ways. The arrays, basically, look like this:

var TreeArray = [0,1,2];
var FruitArray = [4,5,6,7];

I have some links that have an item type and an item id:

<a href='?' class='Link' data-itemid='123' data-itemtype='Tree'>elm</a>
<a href='?' class='Link' data-itemid='789' data-itemtype='Tree'>walnut</a>
<a href='?' class='Link' data-itemid='456' data-itemtype='Fruit'>orange</a>
<a href='?' class='Link' data-itemid='111' data-itemtype='Fruit'>apple</a>

When the link is clicked, the ItemType and ItemID are collected and passed to the addToArray() function:

$Links.click(function(e) {
    e.preventDefault();
    var ItemType = $(this).data("itemtype");
    var ItemID = $(this).data("itemid");
    addToArray(ItemType, ItemID);
});

Here’s where the problem is. If the ItemType is “Tree”, I want to put the ItemID in the TreeArray. If the ItemType is “Fruit”, I want to put the ItemID in the FruitArray. Here’s my function (that doesn’t work):

var addToArray = function addToArray(ItemType, ItemID) {
    var WhichArray = ItemType + "Array";
    WhichArray.push[ItemID];
}

I will have quite a few different types of arrays, not just two. I will have quite a few functions.

So, how can I access these arrays dynamically?

Answer 1

Change your arrays to be properties of an object and then you can access them dynamically by name:

var arrays = {
    Tree: [0,1,2],
    Fruit: [4,5,6,7]
};

var addToArray = function addToArray(ItemType, ItemID) {
    arrays[ItemType].push(ItemID);
}

---

As an alternative, if TreeArray and FruitArray were global variables, you could also access them off the window object like this without changing the array definitions, though I prefer the first implementation above:

// global variables
var TreeArray = [0,1,2];
var FruitArray = [4,5,6,7];

var addToArray = function addToArray(ItemType, ItemID) {
    var WhichArray = ItemType + "Array";
    window[WhichArray].push(ItemID);
}

This works because all global variables are implicitly properties of the window object.