Javascript Objects - Part 1

In Javascript, there is a data structure known as an object, or dictionary in other languages eg. Python. An object is defined using key-value pairs as such:

var obj = {
    key1: value1,
    key2: value2,
    key3: value3
};

where keys are strings and values can be of any type.

To find the value for a particular key, you would then use

var value = obj[key];
// or
var value = obj.key;

To modify the value for a particular key or create the key-value pair if it doesn’t exist

obj[key] = value;
// or
obj.key = value;

An application of this is the popular JSON format which specifies an easy to use syntax for storing data. For example, to store properties of a User Interface (UI) menu item, you could save a JSON file with

{
    "menu": [
        {"text": "Move", "x": 0, "y": 0},
        {"text": "Attack", "x": 50, "y": 0},
        {"text": "Skill", "x": 0, "y": 20},
        {"text": "Item", "x": 50, "y": 20}
    ]
}

For simplicity’s sake, we will assume that the JSON data has been loaded into a Javascript variable jsonstring. To convert the JSON data into a Javascript object

var obj = JSON.parse(jsonstring);

and you can then operate on the object as usual.

On to Part 2: Lookup ->