Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Whenever possible, the developer should always prefer using const over let or var."

A block of code is set as follows:

function myJS()
{
    function add(n1, n2)
    {
        let number1 = Number(n1);
        let number2 = Number(n2);

        return number1 + number2;
    }

}

Any command-line input or output is written as follows:

# php parallel-download.php 

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "If you scroll towards the end of the page, you should now see an xdebug section."

Warnings or important notes appear like this.

Tips and tricks appear like this.