WEBVTT

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In the previous video, we have seen how to create functions this way of creating function is called

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function statement, but there is another way of defining functions, which is called function expression.

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Before we actually see what the function expressions are, let's consider what expression generally

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means in JavaScript.

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For that will be better to compare expressions and statements, you already know what statements are,

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statements or instructions to be executed by the Web browser and statement doesn't produce an immediate

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value.

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As for the expression, it produces a value and can be written wherever that value is expected.

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All right.

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We have already learned what if statement is.

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It uses conditions and the block of code.

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It tells Browsr how to act in different cases and situations, depending on whether condition is true

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or false.

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So if is a statement, and as we said, the statement itself does not produce a value.

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All right, now let's use counsel to demonstrate what expressions are right, a equals two, five plus

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five.

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It's 10:00, this is an expression because it gives us values that right 10 triple equals to a.

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It's an expression, too, because it gives us true, which is a prudent value.

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So, again, statement is an instruction to the browser and it doesn't give us a value.

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And expression always produces a value.

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All right, based on that, now let's consider what function expressions are at first create simple

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function and call it add.

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That place your parameters and be.

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And inside curly braces as a code block writes, consider log A plus B.

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This is a standard function declaration and it's called function statement.

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So why don't we call it.

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With some arguments, five and 10, it gives the Gibralter instruction to execute the code inside a

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function like it was in case of if statement.

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And we have here 15.

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All right, we can define functions in a different way.

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I mean, to assign them to the variable as a value, it's called function expression, so creates variable

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and call it some.

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Then assigned to its function with parameters and be.

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And then, right, Castledare, look, A plus B.

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So here this is a function statement and this is a function expression.

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You may notice that I didn't set function for a function expression, this kind of functions are called

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anonymous functions because they do not have names.

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You may also wonder how can we call the function without name?

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And it's possible using the variable name.

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So let's call this function right.

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Some with the arguments, 10 and 15.

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Revolt, and it's 25.

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All right, there is one important difference between function expressions and function statements,

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that's the first call heds function before function declaration.

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Revolt, and it still works.

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Now, let's do the same for function expression.

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That reload the page.

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And you see, we have type error, which tells us that something is not a function.

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For now, just remember it, because the reason of that difference is an issue of hoisting, hoisting

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is one of the topics regarding how JavaScript works behind the scenes.

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And as we said, it will be discussed in coming sections.

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All right.

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So in this lecture, we have discussed how to define functions in different ways.

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What is difference between function statements and function expressions?

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Functions are more complex things in JavaScript, but at this point, the basic knowledge regarding

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them is enough for you.

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OK, let's go ahead.