The `instanceof` operator tells you whether a given object is an instance of a class.
The `seal()` function prevents adding or removing properties from an object, while still letting you modify existing properties. Here's what you need to know.
The `Object.assign()` function lets you assign properties from one object to another. You can use it to shallow copy objects or assign multiple properties at once.
Arrow functions let you write functions more concisely, but come with several syntactic quirks. This tutorial describes what you need to know to use arrow functions effectively.
Learn about formatting dates using the `toLocaleString()` function, with no outside libraries
Use Mathjs to calculate standard deviation in Node.js and the browser.
Learn what String valueOf(), Number valueOf(), and Date valueOf() have in common.