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Now we know about methods.

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And I did want to talk about methods right now, already,

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because whilst we for the moment

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won't define our own methods too often,

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we will actually work with quite a bit of built in methods

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throughout this and the next sections.

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And here's a good example: up to this point,

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I always used alert for outputting something.

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And the advantage is that we do see that right here on the

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screen, in this alert box.

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The disadvantage is that we always

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have to click it away and so on.

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And since this is all just a dummy example anyways,

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to get started with Java script and learn these basics,

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this of course is not code that does anything useful,

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which we would need on a real page.

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Since that's the case,

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it would be nice to not have this alert,

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but instead we have this console here

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in the developer tools, this console tab.

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And we did see that in here,

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we get error messages that might be caused by our code.

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Well, it turns out that

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we cannot just see possible error messages

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of which we hopefully don't have too many,

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but we can also actively

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output data and information into this console.

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We can log data into this console.

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So that we see it here.

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And during development for learning Java script

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and for playing around with it, that's great.

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It's quicker and simply easier to use,

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than working with that alert box.

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Now for that, we will use a built in object

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provided by the browser and a method

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that's built into this object out of the box.

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And I'll start here, when I first alert something.

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Instead of calling this alert command,

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which has all that built in, I will now remove that,

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and instead use the built in console variable in the end,

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it's provided by the browser,

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which turns out to store an object.

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Hence we can use the dot notation here.

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And now we see there are a bunch of methods built in.

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You learned these purple boxes,

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which are shaped like this, are methods.

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We also have one property here.

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Now for us, the log method is very useful.

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So here I'll select this by clicking on it.

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And now as it's a method,

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we execute it by adding parentheses.

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Now this log method wants a parameter value

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and we can see this. If I hover over it,

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we see that it's a method.

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And then this part here all looks a bit strange,

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but in the end, that means that

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it takes a flexible amount of parameters.

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It's not something we have learned about yet,

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but it means it takes parameters.

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That's all we need to know for now.

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And then this part here void simply means that that's a

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method that won't return any value.

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Void means this method or this function

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does not return anything.

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That's how we can read this.

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And since it takes parameters,

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we can pass total adult years as a parameter,

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we can see that it's takes any kind of value.

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That's what this means.

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So passing in a number,

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which total adult years will be, should be fine.

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And we can do this here as well.

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Replace alert with console.log,

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and also here in our agreed method,

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replace alert with console.log.

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We can use this built in variable and method inside of our

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own method, that works without issues.

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And as a side note,

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if you now hover over your own method here,

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you also get some explanation here by visual studio code.

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We see that it's a method and that this also doesn't return

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anything because we have no return statement in there,

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and that we take no parameters.

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On the other hand for a calculate adult years,

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We see that we need an age.

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Here the type is anything which is technically not correct,

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but visual studio code doesn't understand

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that we need a number in there,

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but we see that it will return a number in the end,

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because we returned a result of this calculation.

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That's just a side note, but also useful to use

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when you want to find out how you can execute your own

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or built in methods and functions, but back to console.log,

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I'm now using console.log

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in all the places where I used alert.

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And if I now a save that, you see that now after reloading,

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you get this output here in this console tab

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in your browser dev tools,

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and that's more convenient than

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having to deal with these alerts.

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And if you reload this page,

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you get this output again, and here you see

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two numbers and then some text, the text is white,

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the numbers are purple, in my case,

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when using this dark mode.

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And that's how we use a built in variable,

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which holds an object, which has this log method.

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And that's why I wanted to introduce methods,

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because console.log is just

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one example of a built-in method, which we'll use a lot.

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We'll use it a lot to output information without using

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alert, which is more disturbing and a bit more annoying.

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Of course, I want to emphasize again,

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that console.log is producing output,

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which we only see in these developer tools

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and the typical user of our page,

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Of course, won't see them.

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Everyone could open these tools,

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but no one typically does that.

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It's just there for us to practice JavaScript.

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We will do more useful things with JavaScript later,

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once we've learned a bit more about it.