Google Maps API 3

CHAPTER 3 ■ CREATING YOUR FIRST MAP
underscores instead of spaces. Another technique is to use camelCasing, which means that each new
word (except the first one) in the variable name starts with an uppercase letter.
var variable name;
var variableName;
Also note that variable names are case sensitive, so variableName and variablename will refer to two
different variables.
■ Warning Always use the var keyword when defining variables. It’s possible to omit it, but doing so
automatically makes the variable global, which means that it will be available everywhere. This might sound
convenient but is in fact the source of many errors and problems, so always try to avoid it. To read more about
why this is bad, read Douglas Crockford’s excellent article “Global Domination” at www.yuiblog.com/blog/
2006/06/01/global-domination/.
Common Data Types
Even if JavaScript is a loosely typed language, it still has different data types. I will briefly describe the
three most basic ones.
Strings
Strings are text. When you define a string, you can use either single or double quote marks around it. I
tend to use single quote marks, but that’s just a matter of personal preference.
var fruit = 'apple';
var fruit = "apple";
But what if you need to have a single or double quote in the string? In these cases, you can use
something called escaping. What this means is that a backslash (\) is inserted before the character being
escaped. The JavaScript interpreter will then know that the character that follows it is part of the string
and discard any other meaning it might have.
var text = 'I\'m hungry';
var myScreen = "I have a 22\" screen";
Worth mentioning also is that to escape a backslash, you put a backslash in front of it.
Numbers
Numbers aren’t enclosed inside quote marks but are simply assigned. All kinds of numbers can be used.
var myAge = 37;
var temperature = -3;
var processorSpeed = 2.66;
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