Now, let's check whether JavaScript works on your machine.
From the tools, select Console. If you cannot find Console, click on the >> symbol, as follows:

Once your console is open, type the following code and hit Enter on your keyboard:
document.write("Hello World");
If you can see the output on the left-hand side panel as shown in the following, then you have successfully configured JavaScript on your browser:

The output that you will see is as follows:
Hello World
Congratulations!
Note
Downloading the example code
You can download the example code files for all the Packt books that you have purchased from your account at http://www.packtpub.com. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register in order to have the files e-mailed to you directly.
If you cannot see the text, check your code or install Google Chrome with administrative rights.
You can also click on the gear button of your console. Check whether Disable JavaScript is unchecked:

You can also debug your JavaScript codes using this tool.
If you type anything wrong; consider that you forgot the inverted commas of the Hello World
string, you will get the following errors:

To speed up writing your codes, you may learn some keyboard shortcuts for both console and Atom text editor.
Here are few keyboard shortcuts for console:
Ctrl + L: Clear console
Tab: Autocomplete common prefix
Right arrow: Accept suggestion
Ctrl + U: Clear console prompt
Up/Down: Next/previous line
Enter: Execute command
Here are few keyboard shortcuts for Atom text editor:
Ctrl + B: Browse list of open files
Ctrl +Alt + R: Reload Atom
Ctrl +Shift + L: Change syntax highlighting
Alt +Shift + S: Show available code snippets
Ctrl +Shift + M: Markdown preview
Ctrl +Alt + I: Toggle Developer Tools
Ctrl + N: New file
Ctrl +Shift + N: New Window
Ctrl + P: Open file (type the name to perform a search)
Ctrl + O: Open file
Ctrl +Shift + O: Open folder
Ctrl + S: Save
Ctrl +Shift + S: Save as
Ctrl + W: Close tab
Ctrl +Shift + W: Close window
Ctrl + G: Go to line
Ctrl + L: Select line
Ctrl +Shift + D: Duplicate line
Ctrl +Shift + K: Delete line
Ctrl + Up/Down: Move line up/down
Ctrl + /: Toggle comment line
Ctrl + Enter: New line below
Ctrl + [/]: Indent/unindent selected lines
Ctrl + J: Join lines
Ctrl + Alt + .: Complete bracket
Ctrl + Alt + M: Select code inside matching brackets
Ctrl + Alt + /: Fold/unfold code
Ctrl + Alt + F: Fold selected code
Ctrl + Alt + [/]: Fold/unfold all code
Ctrl + F: Find in current file
Ctrl + Shift + F: Find in project
F3: Find next
Shift + F3: Find previous
Ctrl + Enter: Replace all
Ctrl + Alt + /: Use Regex in search
Ctrl + Shift + =/-: Increase/decrease text size
Ctrl + 0 (zero): Reset text size
F11: Toggle fullscreen