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: "Edit the increaseValue method again. This time, use the null-check operator."

A block of code is set as follows:

void variablePlayground() {
 basicTypes();
 untypedVariables();
 typeInterpolation();
 immutableVariables();
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

final int numValue = 42; // this is ok
// NOT OK: const int or var int.

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

$ mkdir css
$ cd css

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: "In DartPad, make sure Null Safety is disabled"

Warnings or important notes appear like this.

Tips and tricks appear like this.