New features are added into javascript each time it gets an update, this won't ruin our old code, but it will allow us to be more efficient in the future! I am sure there are already a lot of helpful resources out there to test out the newest javascript features, this will just be a few things we will use in the course.
There are some exercises in the folder
From now on we will be using const and let. Forget var exists! We have talked a little about scope, but here is your chance to put it into practice, check out the examples and figure out what is different.
let is block scoped which means that the program won't know it exists outside of the block.
if (true) {
let newNumber = 10;
console.log("In if scope, number is ", newNumber);
}
// It will throw an error because the variable stays within the if statement
console.log("outside if scope, number is ", newNumber);If we were to use var instead, it would work as intended. Possibly not as intended. And now you see it might be confusing if this was a mistake, calling the variable outside of it's scope, instead of an intended effect!
const are variables that maintain constant values. So we cannot assign them a value and then reassign them a new value.
const greeting = "say Hi";
greeting = "say Hello instead"; // error: Assignment to constant variable. If we need our values to be reassigned, let must be used!
vardeclarations are globally scoped or function scoped whileletandconstare block scoped.
varvariables can be updated and re-declared within its scope;letvariables can be updated but not re-declared;constvariables can neither be updated nor re-declared.
There are some exercises in the folder
You will be expected to use arrow functions for the rest of the course! They are just normal functions using a slightly different syntax, but they also allow us to use some cool updated javascript. Check out the mdn guide on how to break down a normal function into an arrow function. And then use the .js file to practice it yourself!
In the html file, link your script to one of the .js files and check the console in your browser!