Js The — Weird Parts

You are not alone. JavaScript is the quirky, misunderstood genius of the programming world. It was built in 10 days, it drives the modern web, and it has a list of "features" that look more like bugs.

console.log(isNaN(NaN)); // true // But wait... console.log(isNaN("hello")); // true (because "hello" can't be a number) That’s why ES6 gave us Number.isNaN() which actually behaves. In many languages, if you forget to declare a variable, you get an error. In JavaScript (non-strict mode), you get a present : js the weird parts

console.log([] + []); // "" (empty string) console.log([] + {}); // "[object Object]" console.log({} + []); // 0 (wait, WHAT?) The last one is a parsing quirk. In some engines, {} at the start of a line is treated as an empty block, not an object. So {} + [] becomes + [] which coerces to 0. Never, ever trust == . It’s like asking a toddler if two things are the same. You are not alone

Welcome to the weird parts. Let’s start with the most infamous party trick. console