We’re about to step into the future.
So far in this book, we’ve been using JavaScript in its old form. The language recently (in 2015) got a facelift, with a smattering of conveniences and new functionalities added. This new release is called ECMAScript 2015, or ES6 for short. It’s much more enjoyable to use than older JavaScript (ES5), but there’s a problem.
All internet browsers are perfectly capable of running JavaScript, but many users are using older browsers that are not yet capable of running ES6. So, as developers, we want to use ES6, but how can we do so and still have our website work on older browsers?
The key is that ES6 doesn’t do much that ES5 couldn’t do, it just makes it easier to write.
For instance, looping through an array was done like this previously:
var arr = [1, 2, 3, 4];
for (var i = 0; i < arr.length; i++) {
console.log(arr[i]);
}Now, it's done like this:
[1, 2, 3, 4].forEach(num => console.log(num));
An older browser understands the first one,...