Learn TypeScript 3 by Building Web Applications

JavaScript gotchas

Now that you know a bit more about the history of JavaScript, and before we finally dive into TypeScript, we need to learn about the importance of knowing JavaScript, with its good and bad parts.

As you now know, JavaScript was initially created in 10 days, so it had issues, some of which are, unfortunately, still here today. The TypeScript compiler will protect you from some of these issues but it can't change things that are fundamental in JavaScript such as how numbers are represented.

Here are a few examples of things that are surprising (to say the least) in JavaScript:

• JavaScript variables declared with var are function-scoped. For example, if you declare a variable in a for loop, then that variable declaration ...