JavaScript 2.0-The Complete Reference, Second ... - freecodingtutorial

The result is
As you can see, the simpleExample property has undefined value just as any nonexistent
property would.
Note C++ and Java programmers should be aware that JavaScript’s delete is not the same as
in those languages. It is used only to remove properties from objects and elements from
arrays. In the previous example, you cannot delete myString itself, though attempting to
do so will fail silently.
Accessing Properties with Array Syntax
An equivalent but sometimes more convenient alternative to the dot operator is the array ([ ])
operator. It enables you to access the property given by the string passed within the brackets.
For example:
var myString = new String("Hello world");
alert(myString["length"]);
myString["simpleExample"] = true;
alert(myString.simpleExample);
delete myString["simpleExample"];
Some programmers prefer this method of accessing properties simply for stylistic reasons.
However, we‘ll see in later sections another reason to favor it: it can be more powerful than the
dot-operator syntax because it lets you set and read properties with arbitrary names, for
example, those containing spaces.
Methods
Properties that are functions are called methods. Like properties, they are typically accessed
with the dot operator. The following example illustrates invoking the toUpperCase() method of
the String object:
var myString = new String("am i speaking loudly? ");
alert(myString.toUpperCase());
You could also use the array syntax,
var myString = new String("am i speaking loudly? ");
alert(myString["toUpperCase"]());
but this convention is rarely used.
Setting instance methods is just like setting instance properties:
var myString = new String("Am I speaking loudly? ");