Any discussion of JavaScript fundamentals must include an introduction to objects. Because JavaScript fundamental data type is the object. Now objects are simply a collection of values. The variables we've been looking at so far, they've had a single, they've contained a single value while an object allows you to contain multiple values. Those values could be primitive data types, like we discussed already, those primitive data types in an object are called properties. They can be a function, which a function tied to an object is called a method.
It could be arrays, or they could be other types of object objects. So an object can contain a lot of different types of other values. So we have here a sample object, we are referencing this object using the name user one so that's We're going to reference this object, just as with primitive data types that are assigned to variables, you have to have some way to reference them. That's true for objects as well. Now, let's use for this example, this object is going to keep data about a user. And so all the data attached to that object is going to be about a user.
And so this happens to be user one. So let's look at some of the data we could have associated with this object. We could have a username. Now since an object is a collection of values, we need a way to refer to those values. So each value is given a name. In this case, the name of the value is user name, the value is john.
We call we call those collection of values in an object. name value pairs because they can system both the name and the value. So the first data attached to this sample object we're looking at is the username. The value is john. The next name value pair is age the value is 32. address the value is 100. South Main city, the value of Salt Lake City.
So far, this object has four name value pairs. Now let's look at a name value pair that contains different information in this case, a function. So the name is full address, the contents or the value associated with that name is a function definition. So we could execute that function by referring to the object and then referring to the name associated with that function. One Example of data associated with this object. Let's say we're keeping track of comments made by this particular user.
Well, in this case, we could use an array. So an array could be a be associated with an object as well. And once again, it's stored as a name value pair. So the value doesn't have to simply be a primitive like we had with the name value pairs at the top of the object. It can be more than that it could be a function, it could be array could be another object even. Now in JavaScript, when we want to refer to a value, that's a part of one of these name value pairs, we need to reference the name of the value.
And we do that using dot notation. There's actually a couple ways to do that. But right now, we'll just introduce dot notation, and then later in the course, we'll talk about another method for doing this. The way dot notation works is it's done by referencing the object First, and then the name of the name value pair. So if we wanted to extract the username from this particular object, we would do user one dot user name. To show this sample, in a Java JavaScript statement, we can use console dot log.
So it'd be console dot log user, one dot username, and that would display the username. That's the basic way use dot notation to access the name value pairs that are part of an object. We've seen an example of this with the string data type. Now, a string is a primitive, it's not an object. But strings are given an object wrapper and so it allows you to do some additional things with them. If remember, we determine the length of a string.
And we did that using dot notation. So let me open up console. Let me clear this out. Let me create a string. And now we can get the length of that stream using dot notation. We specify the variable and the term length and it will return the length of that string.
This is using dot notation, the same sort of dot notation is available for us with objects. Now the details about how to define an object, and how to work with objects will come later. As we deal with objects. However, there are a couple of built in objects we will be talking about in this fundamental section and that's the date object and the math object. So let's take a look at those