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Welcome back to functions in this lesson, we're going to look at parameters and multiple arguments,

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so arguments are the parameters when they get passed into to the function and we look at them within

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the syntax of the function.

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So then they're known as arguments.

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So it's the same thing.

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Function parameters, so they're inside the parentheses and as we saw, that argument's received by

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the function when it's invoked, so we've got the parameter when it's coming in.

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And then also it's known as an argument when it's being invoked.

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So it's the same thing, but different names for it.

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The function can also have multiple parameters.

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So we can have parameter one, two, three.

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Notice that the comma separated and the structure is the same where we still have that code that's being

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executed.

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So you can also pass in default arguments.

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So there's a number of ways to do that and going to be exploring those as well.

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So we've got some examples here.

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So by default before now, with the newer version of JavaScript, we do have an option to have a parameter

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and equal to a value.

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So that can set the value.

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And before, if we want to be more compatible with older browsers, there's some other ways to do that

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as well, where we can do a conditional statement here so that if we if NUM two is undefined, then

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it will equal five.

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So we've got the value of num to or five.

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So this is another way to set a default typeof num two and if type of num to is undefined we use a territory

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operator.

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So there is a challenge for this lesson.

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So using your knowledge of the earlier lessons, create three different ways to set a default value.

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If a function is missing an argument value, they should all produce the same output.

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And we just showed you that there are three different ways to do that.

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So go ahead, pause the video, open up your editor and try it out.

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And that's also important here to practice passing in those arguments, taking those values and then

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making use of them within the code.

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So let's set up three different functions and we can call them whatever we want.

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In this case, we're going to call it out or one.

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So this one is going to take No.

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One.

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It's going to take number two.

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So just like on our example and we want to set a default value for number two.

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So we are using a more modern browser.

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So we do have access to use the default argument so we can set up with assigned value of five.

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So in this case, will output both those values as into the console so we can have no one can be equal

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to whatever the value that's being passed in of number one.

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And then the other one in the console is going to say, number two, it's going to be whatever value

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of number two is being passed, a few functions that are going to run.

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So in one case, we can pass in one hundred and one hundred.

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So we pass on both of the arguments.

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And then the other case, what we'll do is we'll just pass on one hundred and see what happens.

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And we got to still correct that.

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So that should be two.

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So let's see what the output is.

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So refresh, we're getting number one as one hundred, number two as one hundred.

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And in this case, we didn't pass in a second argument.

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But we are getting that default of five.

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So you could also do something where you've got a default for both of them.

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And if you're not passing in anything, then you can see that the result is the same.

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So you do have that option.

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So the other one that we want it to do is we want to do another function and we can call this one add

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or two.

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And this is going to take in those same two arguments.

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And this is four older versions of browsers that might not have this default argument value here, where

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we're going to use a conditional statement to check to see if NUM two is equal to a value.

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So if there is a value here, then it's just going to assign that value.

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If there's no value there, then it's going to sign the value of five to it and we can try that in this

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case as well.

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So just update this to number two.

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Number two, and in this case, we do need to pass the first argument and you can see that it sets a

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default for the second one.

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And we'll try one last one.

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And this is the one that's also more commonly used as well, where we actually check the type of number

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two, so do type of number two.

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And if the type is not equal to undefined, then all we do is we just output number two.

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So that means that there is a value there.

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Otherwise we're going to set a value of five and we'll try this one out as well.

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And I'll update this to 100.

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So we refresh it.

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And you see, in this case, we do pass one hundred and one hundred and then this one is equal to one

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hundred, and the second value is being set by default.

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So coming up, even more on functions coming up in the next lesson.