JavaScript Basics

In this chapter, we will explore JavaScript values and variables!

There are a few different ways to run JavaScript code. The easiest to get started is to use the browser console; open the development tools and the console tab.

Console

When creating a web application, you can use console.* to output information to the browser console.

Console is a very handy tool for quickly debugging problems.

Interestingly, there is no specification for how console.* methods behave in ECMAScript. Each browser (environment) adds its own methods and behavior. However, almost all environments support the following:

• Logging information such as printing out a message or the current value of a variable

  console.log("This is my message");
  

• Sending a warning to the console.

  console.warn("Resource not changed")
  

• Sending an error message to the console.

  console.error("File not found!")
  

You should not include any console.* methods in production code.