Functions are an essential part of program design. You can use functions to break up a large solution into individual components and to create libraries of behaviors that can be used by your programs. We have used some built-in functions (for example, alert) and created event handler functions (for example, doCheckAge). In this chapter, you’ll learn how to create and use functions of your own. You’ll see how to give functions data to work on and how a program can receive results that a function returns. Along the way, you will pick up some tips about error handling.
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