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

Modifying the values of an array is just as easy. To change the second value of the array, just
assign it like this:
myArray[1] = 101;
Of course, when setting array values, you must remember the distinction between reference
and primitive types made in previous chapters. In particular, recall that when you manipulate a
variable that has been set equal to a reference type, it modifies the original value as well. For
example, consider the following:
var firstarray = ["Mars", "Jupiter", "Saturn"]
var secondarray = firstarray;
secondarray[0] = "Neptune";
alert(firstarray);
You‘ll notice, as shown here, that the value in firstArray was changed!
This aspect of reference types is very useful, particularly in the case of parameter passing to
functions.
Removing Array Elements
Array elements can be removed using the delete operator. This operator sets the array element
it is invoked on to undefined but does not change the array‘s length (more on this in a
moment). For example,
var myColors = ["red", "green", "blue"];
delete myColors[1];
alert("The value of myColors[1] is: " + myColors[1]);
results in