The Array Object

The Array Object

We've already seen the Array object in Chapter 2 (see the section "Arrays" in Chapter 2), but we haven't taken an in-depth look at the Array object itself. We'll do that here. You can see an overview of the properties and methods of the Array object in Table 19.9, its properties in depth in Table 19.10, and its methods in depth in Table 19.11.

Table 19.9. Overview of the Properties and Methods of the Array Object

Properties	Methods
constructor	concat
length	join
prototype	pop
	push
	reverse
	shift
	slice
	sort
	splice
	toLocaleString
	toString
	unshift

Table 19.10. The Properties of the Array Object

Property	NS2	NS3	NS4	NS6	IE3a	IE3b	IE4	IE5	IE5.5	IE6
constructor		x	x	x		x	x	x	x	x
	Read/write
	This property specifies the function that creates an object.
length		x	x	x		x	x	x	x	x
	Read/write
	This property holds an integer value one higher than the index of the highest element in an array. Note that because elements don't have to be contiguous, this property does not technically have to reflect the total number of elements in an array!
prototype		x	x	x		x	x	x	x	x
	Read/write
	This property returns a reference to the object's prototype. You use the prototype property to provide base functionality to a class of objects. See "Using the prototype Property" in this chapter.

Table 19.11. The Methods of the Array Object

Method	NS2	NS3	NS4	NS6	IE3a	IE3b	IE4	IE5	IE5.5	IE6
concat			x	x			x	x	x	x
	Returns: Array object
	This method concatenates (joins) two arrays together and returns the result.
	Syntax: array1 .concat( array2 ) .
join		x	x	x		x	x	x	x	x
	Returns: String
	This method returns a string holding all the elements of an array joined together, separated by a separator string.
	Syntax: array .join( separator ) , where separator is the separator string you want to appear between elements in the returned string.
pop			x	x					x	x
	Returns: Array entry
	This method "pops" the array by removing the last element from an array and returning it. See "Pushing and Popping" in this chapter.
	Syntax: array .pop() .
push			x	x					x	x
	Returns: Array entry
	This method "pushes" a new element or elements onto an array by appending them to the end of the array and returning the new length of the array.
	Syntax: array .push( item1 [, item2 ... [, itemN ]]) . See "Pushing and Popping" in this chapter.
reverse		x	x	x		x	x	x	x	x
	Returns: Array object
	This method returns the array with the order of the elements reversed .
	Syntax: array .reverse() .
shift			x	x					x	x
	Returns: Array entry
	This method removes the first element of an array and returns that element.
	Syntax: array .shift() .
slice			x	x			x	x	x	x
	Returns: Array object
	This method returns a slice, or section, of an array.
	Syntax: array .slice( start , end ) ; where start is the beginning index of the slice, and end is the ending index of the slice.
sort		x	x	x		x	x	x	x	x
	Returns: Array object
	This method sorts an array.
	Syntax: array .sort([ function ]) ; where function is a function that returns a negative value if the first argument passed to it is less than the second argument (according to the way you want to sort the items), zero if the two arguments are equal, and a positive value if the first argument is greater than the second argument. If you omit function , the array is sorted in ascending text order. See "Sorting Arrays" in this chapter.
splice			x	x					x	x
	Returns: Array object
	This method removes elements from an array and can also insert new elements. This method returns the deleted elements.
	Syntax: array .splice( start , count [, item1 [, item2 [, ... [, itemN ]]]]) ; where start is the location at which to start deleting elements, count is the number of elements to delete, and item1 to itemN are elements to insert to replace the deleted elements.
toLocaleString				x					x	x
	Returns: String
	This method returns the array in locale-sensitive string form.
	Syntax: array .toLocaleString() .
toString		x	x	x		x	x	x	x	x
	Returns: String
	This method returns the array in string form.
	Syntax: array .toString() .
unshift			x	x					x	x
	Returns: Array entry
	This method returns the array with the given elements inserted at the beginning.
	Syntax: array .unshift(([ item1 [, item2 [, ... [, itemN ]]]]) , where item1 to itemN are elements to insert at the start of the array.