Transcript

          
        
          Okay then.

          So we've seen how to store different data or values in variables.
          
          We saw that in the last video, but at the minute all of those different values were just numbers.
          
          We did things like an age a year or points or a score.
          
          They were all numbers, right?
          
          And that is just one data type in JavaScript.
          
          Now in JavaScript we work with many different data types.
          
          The seven in total, they're all listed here and they all have their own unique properties and the things
          
          that they can do.
          
          So we're going to have a quick run through of all of them now.
          
          But as we go into the course, we'll be looking at each one in much more detail and using them all as
          
          we go through them.
          
          So then first of all, numbers, we've seen them in action already.
          
          Things like one, two, three, 100 or 3.14, even decimals like this, they are all of the number type.
          
          The next one right here, this is a string.
          
          And strings are basically a series of characters in single or double quotes, like a sentence or some
          
          kind of email like this.
          
          Okay, the next one, Booleans over here, they are a special, logical, true or false value.
          
          Not in quotes, they're not strings.
          
          And we use these for evaluating conditions.
          
          Now, this next one null over here.
          
          This is a way that we can explicitly say that a variable has no value.
          
          So we could create a variable but set it equal to null to say that that variable doesn't have a real
          
          value yet.
          
          Okay.
          
          Now it's closely related to undefined here, but the difference is undefined is a type that's given
          
          to variables automatically by the browser that have not yet been defined.
          
          So these are both empty values, but this one right here null.
          
          We explicitly set to a variable.
          
          This one is automatically given to variables when they're not yet defined.
          
          Does that make sense?
          
          Okay, so the next type, this object thing right here, these are more complex data structures which
          
          can have multiple different properties and functions, meaning they can perform various different things.
          
          Now a lot of JavaScript is based around using objects and there are many different object types or types
          
          of objects built into the language which we can use out of the box.
          
          There's a whole subset of built in object types like arrays, dates, object literals.
          
          In fact, you might hear the saying everything in JavaScript is an object, which is a huge simplification,
          
          but it stems from a source of truth.
          
          But don't worry about that.
          
          Now.
          
          There will be a whole chapter on objects later on in the course and we will look at all the different
          
          types of objects we can use in JavaScript as well.
          
          Things like arrays and dates and object literals.
          
          Okay.
          
          And finally, symbols.
          
          They are a new addition to the JavaScript language which are closely linked to objects too.
          
          So we're going to discuss them more later in the course rather than now.
          
          So for the rest of this chapter, we're going to be looking at these different types of data like strings,
          
          numbers, null undefined and booleans.
          
          We'll also have a quick look at arrays which fall under the object type down here.
          
          It's a type of object with its own unique properties, but we use them all the time in JavaScript and
          
          they're quite simple to learn, which is why I'm covering them in this chapter.
          
          Now.
          
          A variable which we've already seen can hold any data type, be it a string, a number null boolean,
          
          an object.
          
          ET cetera.
          
          We don't have to explicitly say what type of variable it will store or what type of data it will store,
          
          and we can override a variable with a different type too.
          
          Meaning if we make a variable and store a string in it to begin with, we can override it later on If
          
          we use the let keyword that is with a number.
          
          Okay.
          
          So we can change the type of variables.
          
          And for that reason, JavaScript is known as a loosely typed language, in contrast to a strongly typed
          
          language like Ruby or Python.
          
          Now I don't want you to feel overwhelmed with all the different types or think you have to remember
          
          them all.
          
          Don't focus on that because the more you code with JavaScript, it's going to come naturally to you
          
          over time.
          
          And we're going to be referring back to this type chart anyway throughout the course to reinforce your
          
          understanding of them.
          
          The last thing I want to do is scare you off.
          
          So as long as we have the idea of types simmering in the background, that is more than good enough
          
          for now.