Best of Modern JavaScript — Handler Methods

Useful methods we can add to change object behavior.

Since 2015, JavaScript has improved immensely.

It’s much more pleasant to use it now than ever.

In this article, we’ll look at how to control JavaScript object operations.

Make Objects Non-Configurable

We can make objects non-configurable.

This means that we can’t change the property descriptor of an object.

The property descriptors include the property value, whether the property is writable, or whether it’s configurable.

Configurable means the ability to change the property descriptions of an object.

To disable configurability, we can write:

const obj = {};
Object.defineProperty(obj, 'foo', {
  value: 'bar',
  writable: false,
  configurable: false
});

We defined the obj.foo property with the Object.defineProperty method.

The 3rd argument has the property descriptors.

configurable set to false lets us disable changing property descriptors.

We also set writable to false so that we can’t change the value of the foo property’s value.

The enumerate Trap

ES6 proxies was originally going to include the enumerate trap to lets us change the behavior of the for-in loop.

But it’s removed to simplified proxies.

javascript technology programming

Exercise from Eloquent JavaScript. Today, we will write a function that forms a chessboard. You can find the exercise in the Eloquent Javascript book (3rd edition, chapter 2; Program Structure). Write a program that creates a string that represents an 8×8 grid, using newline characters to separate lines. At each position of the grid there is either a space or a “#” character. The characters should form a chessboard.

One of the nice things about learning JavaScript these days is that there is a plethora of choices for writing and running JavaScript code. In this article, I’m going to describe a few of these environments and show you the environment I’ll be using in this series of articles.

To paraphrase the title of an old computer science textbook, “Algorithms + Data = Programs.” The first step in learning a programming language such as JavaScript is to learn what types of data the language can work with. The second step is to learn how to store that data in variables. In this article I’ll discuss the different types of data you can work with in a JavaScript program and how to create and use variables to store and manipulate that data.

Professor JavaScript is a JavaScript online learning courses YouTube Channel. Students can learn how to develop codes with JavaScript from basic to advanced levels through the online courses in this YouTube channel.

Async callbacks or promises. Introduction to JavaScript Async Programming