Learning jQuery - Fourth Edition

Appendix A. JavaScript Closures

Throughout this book, we have seen many jQuery methods that take functions as parameters. Our examples have thus created, called, and passed around functions time and again. While usually we can do this with only a cursory understanding of the inner JavaScript mechanics at work, at times side effects of our actions can seem strange if we do not have knowledge of the language's features. In this appendix, we will cover:

• JavaScript's ability to define functions within other functions
• Ways in which function objects can be passed around
• The scope of variables defined inside and outside functions
• Common problems caused by variable scoping and closures
• How jQuery constructs interact with function definitions
• Memory issues that ...