Alright guys, so we've learned about boolean operators, strings, integers, etc.
We learned how to redefine variables. What we're going to be learning about in
this video is how to compare values. So, the most basic way to compare two values
to check if something is true, and that's what we're doing essentially
we're checking if something is true or false. It's called a truth checking, I
guess. What we're going to be doing first is checking what we've done is
we've checked if something equals something else, and again you can say
does true == true, and that's going to say true. Or, we can say does "hi" == "hi" and it's
going to return true. But, if we say "hi" == 3 it returns false because it is
not the same. So you use two equal signs to compare values, and you use one equal sign to
assign values. So if I said "hi" = 3 it's going to freak out because it
doesn't know what I'm doing there. A string never goes on the left of something, or
an integer. You can do 5 = 6 and invalid left hand side in assignment. So,
basically it knows we're assigning a value to something because we're using
the equal sign we have a value there for it, but we can't assign
that to an integer. We can assign it to a variable, and so if we create a variable
called mynum we can set it to 6. Now every time we print out mynum it's
going to use 6. So here we could say is mynum == 6, and that's
the most common reason you'll find fact-checking, or truth checking, is to
see if a variable is equal to something. So, let's say that I have started a
website that can let people sign up, and if they choose to they can purchase a
premium service, or a subscription. So, I'm going to create a variable let's assume
that I'm a user right now and my variable is set to isPremiumUser, and
I'm not. So, let's say we only want to provide a bit of code or we want to do
something special if the person is a premium user. So, we would
compare that isPremiumUser, and is that equal to true and if it is we can do
something, but it's not so we're not going to do anything, and that brings us
into if statements. If statements are basically a way to apply this and do
something based on the result, whatever we want to, but we're not quite
done with comparisons. We can also compare if something is not equal to
something else. So, if isPremiumUser is not equal to true then maybe we'll say,
hey, you should buy this, you know, or you should subscribe as a
premium user. So, the operators to use when comparing if something is not equal
to another one is to use an exclamation point followed by an equal sign, and
these operators right here means is not equal to. Basically, in programming, not
just in JavaScript but in PHP and other languages, the exclamation sign means not.
So by combining it here you're saying not equal, basically. You can also compare
greater than or less than. So we can say is 5 less than 7, and it is true. Now we
can also say is 7 less than 7 and it's going to say false, but if I said is
7 greater than 7 it also says false. So, maybe we want to
run a bit of code, and I'll show you guys examples as soon as we get into if
statements, but maybe we want to compare if a number is greater than or equal to
a number. So, we would say is 7 greater than equal sign 7. It's going
to return true because 7 is equal to 7,
it's not greater than. You can do the same with a less than. 7 is less than or
equal to 7, and that's going to return true as well. So, with all that said, let's
start writing if statements. And for if statements we are going to move back to
our IDE, and we're going to be running this page every time we want to update
it.