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Brian introduces builtins by teaching students how to utilize MDN as a valuable resource.

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Transcript from the "Builtins" Lesson

>> Brian Holt: Now I've showed you how to write your own functions, right? JavaScript has a bunch of them, just kind of built in for you, which is really nice. Right? Stuff that, like, you're going to do so many time charts, just like here, we're just going to write that for you so you don't have to do it every damn time.

So like here, const sentence, this has weird casing in it. Also known as, I did not make this up SpongeBob casing. [LAUGH] Okay? console.log(sentence.toLowerCase), right? So sentence is a string, right? So you won't expect a string to have a function on it, but it does. It has actually quite a few functions on it.

One of them is toLowerCase, that will take all of, everything inside of your string and make it lowercase. So that's why when you log this out, it has everything in lowercase, right? Now, you could probably guess, toUpperCase works as well.
>> Brian Holt: And there's just a bunch of those on there.

But the things to be aware of that you can do, right?
>> Brian Holt: So I'm a big fan of MDN, which stands for Mozilla Developer Network, which is made by the same people that do Firefox. It's like the definitive reference for JavaScript. So I would recommend getting very familiar with that website.

>> Brian Holt: It's It's translated into every language that you possibly want to know, or at least, many. So I can come in here and I can say, toUpperCase, search for it. And the first thing you're gonna see is String.prototype.toUpperCase().
>> Brian Holt: That's cool. I don't know they have workable demos now.

It's even better than it used to be, right. Now, if I click Run, it will actually show me the results of that. But it'll tell you like, okay, this is what it does, this is what the return value is. It's quite technical because it is technical documentation. But I'm constantly referencing this.

I would say this is the best for learning how things work, what exists, how to get it to work, and such. They have lots of examples. It's good.