TypeScript

TypeScript is a strict superset of JavaScript, the language that powers the web. It took developers over 20 years to make JavaScript usable (by introducing TypeScript), because JavaScript has one major flaw: It's dynamically and loosely typed, which is a huge PITA... Long story short, 0 == "0" is true, 0 == [] is true, but "0" == [] is false. As a result, the === syntax was introduced, which is for type-script comparisons, where all of the above are false.

TypeScript will tell you that these are bad comparisons, because it has a proper type system that can catch these kinds of stupid errors. TypeScript's syntax will feel natural to you due to its similarity with Java. Key differences:

• Variables: let myVar = false (type inference) or with static typing let myVar: boolean = false
• Functions: In ECMAScript 6 (and higher, which we are using here), functions are assigned to constants. You can use the function syntax, but it's really not the idea to do so. You define a function using const myFunc = () => {}.

That's the key differences. There are also classes, but please don't use them, it's not the JS/TS way. JS is more of a functional programming language than an object oriented one because it doesn't have proper access modifiers.

The superpower of JS is its anonymous objects, which you can type using interface declarations. This is the only "JS approved" object orientation.