What are arrow functions?

- You know how, when you create anonymous functions in JavaScript, so maybe you're creating a function expression, or you're using a function inside an event listener or something like that. You end up writing out a bunch of code that seems unnecessary. Case in point, standard function expression. So here we have the var sumTotal. Then we create an anonymous function that grabs the two properties, price and tax. Then we return, price times tax over 100 plus one. So that gives us the price plus whatever tax value on top of that. And then we console log out sumTotal, six and 12, so that would give us $6 plus 12% tax is, like, 7.64, whatever. So this works fine, but you see that this function expression here is really clunky. We have to declare that we have a function. But this is a throwaway anonymous function. We're only going to use it once, it doesn't have a name. And it's captured inside this variable anyway. So this syntax seems unnecessary, especially because, for this function expression to work, we need to return to value, otherwise there's no point putting it inside a variable to begin with, eh? So that's why we now have this thing. This arrow, fat arrow, an arrow function. So this is an equal sign, uh, this is an equal sign, plus a bigger than symbol, and it looks like an arrow. Poof, finding, going in that direction. This function here makes things a lot easier because with an arrow function, we can do the exact same thing with a lot less code. And it's actually easier to read, once you understand how to read it. So we're saying the same thing. We have this variable called sumTotal, and we're going to capture a function inside it. So anytime we call the variable and pass some properties to it, then we get the result return back. Now, this time we're using an arrow function, so we're saying inside sumTotal, we are taking the two properties, price and tax. Then we are sending it over to this calculation here, and the calculation, it returns the result to sumTotal. So we're saying price and tax, send to price times tax over 100 plus one, let me return the result. So when we go down here and say console, log, sumTotal, six, 12, we get the same result. Except this is much cleaner than that old function expression. Now, like I said, you'll see these arrow functions used either in anonymous functions or in function expressions like here, and you'll also see them used a lot inside event listeners. Because that's when, if you have some sort of anonymous function you need to execute inside an event listener, you then have the writing your event listener and then saying function, parentheses, and then curly brackets, and then blah, blah, blah, blah, blah, blah. And it becomes really hard to read. And then you solve that by then breaking that out into a separate function that you can then call from the event listener, and it gets really clunky. Well, with this arrow function, you can get that to be a lot cleaner because you don't have to declare the function and it can make it really tight and small. In fact, if you have an empty, like, if you have an anonymous function that doesn't have any properties to it, you just put in the two parentheses, and then you put the arrow after, and then you say what you want, and that automatically gets returned. So that's why the arrow function exists. That's how to read it, and that's why you'll end up using it.