JavaScript Examples Bible - UserWorks Technologies

String and
Number Objects
(Chapters 34
and 35)
Knowing how to manipulate strings of text characters is a
vital programming skill. You may not have to do it all
the time, but you should be fully aware of the possibilities for
this manipulation that are built into whatever programming
language you use. In JavaScript (as in any object-based or
object-oriented language), strings are objects that have
numerous properties and methods to assist in assembling,
tearing apart, extracting, and copying chunks of strings.
Any characters that users enter into text boxes become
parts of string objects. In IE4+ and NN6, text inside HTML
element tags can be treated as strings. In IE4+, you can even
work with the HTML tags as strings. Therefore, of all the core
language objects to implant in your scripting consciousness,
the string object is it (arrays, whose examples come in the
next chapter of this book, rank Number Two on the list).
Numbers are much less frequently thought of as objects
because they tend to be used as-is for calculations. JavaScript
1.5 in recent browsers, however, endows the number object
with practical methods, especially one that (finally) offers
built-in control over the number of digits displayed to the
right of the decimal point for floating-point numbers.
When examples in this chapter encourage you to enter a
sequence of expressions in The Evaluator, be sure to follow
through with every step. But also make sure you understand
the results of each expression in order to visualize the particular
method operates.
16
C H A P T E R
✦ ✦ ✦ ✦
In This Chapter
Parsing text at the
character level
Performing searchand-replace
operations with
regular expressions
Converting between
character codes and
text
Setting number
format and precision
✦ ✦ ✦ ✦