JavaScript & jQuery: The Missing Manual ... - Robert Guajardo

Going Further with
Java Script
This chapter covers various concepts that can help make you a better JavaScript
programmer. You don’t need most of the ideas here to write functioning JavaScript
programs, so don’t worry if you don’t understand them all. The first
few sections provide helpful tips and methods for working with strings, numbers,
and dates, and once you’ve mastered the basics, these sections can really help you
process visitor input in forms, work with HTML and HTML attributes, and generate
dates for calendars. The section “Putting It All Together” on page 457 contains some
good advice for beginners, but you can program happily for a long time without
needing the information in the other sections in this chapter. But if you want to
expand your skills, this chapter can point you in the right direction.
Working with Strings
Strings are the most common type of data you’ll work with: input from form fields,
the path to an image, a URL, and HTML that you wish to replace on a page are all
examples of the letters, symbols, and numbers that make up strings. You learned the
basics of strings in Chapter 2, but JavaScript provides a lot of useful methods for
working with and manipulating strings.
Determining the Length of a String
There are times when you want to know how many characters are in a string. For
example, say you want to make sure that when someone creates an account on your
top secret website, they create a new password that’s more than 6 letters but no more
than 15. Strings have a length property that gives you just this kind of information.
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