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All right, welcome back here on lesson seven, boolean logic, Boolean is named after a man, George

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Bush.

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He was an old mathematician in the eighteen hundreds and he really kind of defined the terms that we

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have for logic.

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And that's used a lot in mathematics and use fantastically in programming.

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It's used all over the place in programming.

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Basically, he invented and worked on very primitive computers and algebraic problems, boolean logic.

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So a couple of different operators we have.

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And and that's and that means both of the values to the left and right of this operator have to be true

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or means if one of the values or both to the left and right of this are true, it will continue.

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The exclamation mark is usually is paired with other operators.

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So like exclamation equals would be not equals.

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As you can see here, we're not exactly equal to.

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And then you have these others as well, these are other comparison operators, this is similar to work

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in Group two or the exactly the same as this is the same value and data type.

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This is less then and less than or equal to the left.

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Carrott right is right here is greater than greater than or equal to.

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So the value on the left is greater than the value on the right.

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And they have some bitwise operators.

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We can look at these as well.

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We don't use bitwise operators very often in JavaScript, but there they operate on a bit string, a

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bit array or binary numeral at the level of individual bits.

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So it's it's kind of what computer programming does at a more basic level.

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And you can perform those on binary numbers as well, too.

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OK, so let's take a look at some values in code.

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All right, so now in JavaScript, let's just focus on some of the ones we use most most often.

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So let's just say let the equation equal five is greater than two.

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And so we could just check to see, is this true, so we could just along the variable itself

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equation and then we'll see, hey, is five greater than two?

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And the answer is yes, it is true.

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Now, if we check, is it less than two, that's false.

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Five is not less than two, is it less than or equal to two?

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No, that's false.

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Is it less than or equal to five?

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Yes, five is less than or equal to five, because five is equal to five is five less than five.

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No, that's false.

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So you could say you could use these comparison operators to check something less than or less than

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or equal to something.

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And then you can use five is greater than two and

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two is greater than one.

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OK, so let's just see how this goes.

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Let's just read this right now.

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True.

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OK, so five is greater than two, that's true.

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Two is greater than one.

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That's true.

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Also, OK, these are both true and this says both have to be true.

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And so this is true.

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And this is true.

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So if we change this one to four and we check it again.

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It's false because, too, is not greater than four, so since this site is true, this site is false,

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it's true and false, which means the total is false.

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There's any false value in there, then the whole thing is false.

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OK, because that's the final value that's being checked.

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Rechecking, checking.

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Is this true?

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Yes.

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And is this true now?

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OK, so are they both true?

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No, that's the real question.

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Now, if he chooses to or then one of them being true is OK, as you can see, that's true.

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What if we make them both false?

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OK, we make them both false, then boom, neither one is false or is asking.

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Is at least one of these true?

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That's what Gore is asking.

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OK, so that's how you get and and or there's also not we can say this

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five equals five.

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OK, is that true.

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Yes.

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Five is equal to five.

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You can also do ten divided by two is five.

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Exactly the same is ten.

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Divided by two.

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Yes, because ten divided by two is five.

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What if we say is not equal to.

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Let's check that.

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No, that's false.

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Five is not not equal to five.

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So let's try again with let's change this value to four.

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Is four different then.

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Ten divided by two.

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Yes, the answer is true.

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There you go.

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So that's how you can use equals to say is the same as not equals with the not symbol to say is not

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the same as.

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OK, just beware.

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Obviously, you might have gotten a little tripped up when I was saying, hey, is this not the same

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as the other thing.

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And you say yes or no humans, especially in English, have a hard time asking and answering questions

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which involve not only is this not the same, what are you supposed to say to that?

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Yes or no?

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So we keep it simple in JavaScript, true or false, but still beware of using not just so you don't

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get confused with what you need to do.

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OK, all right.

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So that is the basics of boolean logic in JavaScript and we'll catch you in the next video.