Builtins
Lots of functions already exist for you! Smart people have created this commonly-used functions for things we often need. For example, say you have a string and you want to make everything lowercase, you can do this:
const sentence = "ThIs HaS wEiRd CaSiNg On It";
const lowerCaseSentence = sentence.toLowerCase();
console.log(lowerCaseSentence);
Always be looking for the parens. And the best place to look all this stuff up is from our friends at Mozilla (makers of Firefox): the MDN. MDN used to stand for "Mozilla Developer Network" I think but now it's just synonmous with the documentation for the web. I literally look at this website several times a day. As I said before, you are not expected to remember everything. Looking things up on the MDN is not cheating.
There are so many builtins there's no way we could ever cover all of them. Here's just a few examples. The rest you'll learn as you go.
// want to round a number? use Math!
const number = 5.3;
const roundedNumber = Math.round(number);
console.log(number);
// want to see if a string contains another string?
const testStringOne = "The quick brown fox jumps over the lazy dog";
const testStringTwo =
"Mirror, mirror on the wall, don't say it cause I know I'm cute";
const stringToLookFor = "cute";
console.log(testStringOne.includes(stringToLookFor));
console.log(testStringTwo.includes(stringToLookFor));
// want to know how many milliseconds have elapsed since Jan 1 1970?
console.log(Date.now());
