[egghead.io] JavaScript Handy Tips & Tricks

ES2019 introduces the Array.prototype.flat method. In this lesson, we'll flatten a multidimensional array using Array.prototype.reduce and Array.prototype.concat, and then refactor the code to do the same thing using the .flat method. We'll then use the depth parameter to flatten a 3 dimensional array.

ES2019 introduces the Array.prototype.flatMap method. In this lesson, we'll map and flatten a multidimensional array using Array.prototype.map, Array.prototype.reduce and Array.prototype.concat, and then refactor the code to do the same thing using the .flatMap method. Then, we'll see how we can use empty arrays in our map function to act as a filter before mapping.

In this lesson we'll learn how to refactor es5 functions into es6 arrow functions to decrease visual noise in our program. We'll take a step by step approach, increasing clarity with each rewrite.

In this lesson we are going to learn how to set default values to variables destructured from a JavaScript object, which may come in handy if we'd like to avoid setting those variables to `undefined` because a certain field is not specified in the object we are destructuring from.

In this lesson we are going to learn how to remove unwanted properties from a JavaScript object following an example of an object containing sensitive data (such as password and bankBalance) and removing this kind of data from it. To achieve that we are going to use two ES6 features: destructuring an object and the spread operator.

In JavaScript, we often end up composing one object out of several other objects. Luckily there's a convenient [spread operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax) which allows us to spread entries from one object to another. Sometimes we only want to include something in the newly created object if a certain condition is met

Even though JavaScript is a very dynamic language, sometimes we want to be _extra_ sure that it's not possible to modify an object once it was declared. Luckily, there's a method called `Object.freeze` which allows us to freeze an object so it's not possible to modify it in any way whatsoever once it was initialized. In this lesson we are going to learn how to use `Object.freeze`

Sometimes it's necessary to have a fixed set of properties on a JavaScript object, while also maintaining the option of changing those properties. In this lesson we are going to learn how to use `Object.seal()` method to prevent new properties from being added to it and marking all existing properties as non-configurable. Values of present properties can still be changed.

Sometimes we'd like to ensure that some `console.log` are *really* visible one someone opens dev tools window. For instance, we could want to warn our less tech-savvy users that they shouldn't paste anything someone else send them to console, because their account might get stolen. In this lesson we are going to learn how to style `console.log` messages with CSS properties so we c

Chrome DevTools provide many handy utility functions that we can use to make debugging faster and easier so we can fix the bug and move on. In this lesson we are going to learn how to use `$`, `$$` utilities built-in in Chrome DevTools to get references to single and many DOM elements and how to use `$0 - $4` variables to reference object selected using Inspect Element tool.