JavaScript by Example: JavaScript Core Objects. Pt. 1

Property

What It Does

constructor

References the object's constructor

length

Returns the number of elements in the array

prototype

Extends the definition of the array by adding properties and methods

<html>

<head>

<title>Array Properties</title>

<h2>Array Properties</h2>

1 var book = new Array(6); // Create an Array object

book[0] = "War and Peace"; // Assign values to elements

book[1] = "Huckleberry Finn";

book[2] = "The Return of the Native";

book[3] = "A Christmas Carol";

book[4] = "The Yearling";

book[5] = "Exodus";

</script>

</head>

document.write("<h3>");

2 document.write("The book array has " + book.length

+ " elements<br>");

</script>

</body>

</html>

(Output)

The book array has 6 elements.

A six-element Array object is declared.

The length property is used to get the length of the array. The length is 6.

Array methods.
Method	What It Does
concat()	Concatenates elements from one array to another array
join()	Joins the elements of an array by a separator to form a string
pop()	Removes and returns the last element of an array
push()	Adds elements to the end of an array
reverse()	Reverses the order of the elements in an array
shift()	Removes and returns the first element of an array
slice()	Creates a new array from elements of an existing array
sort()	Sorts an array alphabetically, or numerically
splice()	Removes and/or replaces elements of an array
toLocaleString()	Returns a string representation of the array in local format
toString()	Returns a string representation of the array
unshift()	Adds elements to the beginning of an array

Array methods.

Method

What It Does

concat()

Concatenates elements from one array to another array

join()

Joins the elements of an array by a separator to form a string

pop()

Removes and returns the last element of an array

push()

Adds elements to the end of an array

reverse()

Reverses the order of the elements in an array

shift()

Removes and returns the first element of an array

slice()

Creates a new array from elements of an existing array

sort()

Sorts an array alphabetically, or numerically

splice()

Removes and/or replaces elements of an array

toLocaleString()

Returns a string representation of the array in local format

toString()

Returns a string representation of the array

unshift()

Adds elements to the beginning of an array


newArray=oldArray.concat(new elements); Example: names = names.concat("green, "blue");

newArray=oldArray.concat(new elements);

Example:

names = names.concat("green, "blue");


<html> <head><title>Array concat() methods</title> </head> <body> <script language="JavaScript"> 1 var names1=new Array("Dan", "Liz", "Jody" ); 2 var names2=new Array("Tom", "Suzanne"); document.write("<b>First array: "+ names1 + "<br>"); document.write("<b>Second array: "+ names2 + "<br>"); document.write("<b>After the concatenation <br>"); 3 names1 = names1.concat( names2); document.write(names1); </script> </body> </html>

<html>

<head><title>Array concat() methods</title>

</head>

<body>

1 var names1=new Array("Dan", "Liz", "Jody" );

2 var names2=new Array("Tom", "Suzanne");

document.write("<b>First array: "+ names1 + "<br>");

document.write("<b>Second array: "+ names2 + "<br>");

document.write("<b>After the concatenation <br>");

3 names1 = names1.concat( names2);

document.write(names1);

</script>

</body>

</html>


The first Array object, called names1, is created.
The second Array object, called names2, is created.
After concatenating the names2 array to names1, the result is returned to names1. The concat() method allows the elements of one array to be added to another.

The first Array object, called names1, is created.

The second Array object, called names2, is created.

After concatenating the names2 array to names1, the result is returned to names1. The concat() method allows the elements of one array to be added to another.


var return_value=Arrayname.pop(); Example: var popped = myArray.pop();

var return_value=Arrayname.pop();

Example:

var popped = myArray.pop();


<html> <head><title>Array pop() method</title> </head> <body> <script language="JavaScript"> 1 var names=new Array("Tom", "Dan", "Liz", "Jody"); 2 document.write("<b>Original array: "+ names +"<br>"); 3 var newstring=names.pop(); // Pop off last element of array 4 document.write("Element popped: "+ newstring); 5 document.write("<br>New array: "+ names + "</b>"); </script> </body> </html>

<html>

<head><title>Array pop() method</title>

</head>

<body>

1 var names=new Array("Tom", "Dan", "Liz", "Jody");

2 document.write("<b>Original array: "+ names +"<br>");

3 var newstring=names.pop(); // Pop off last element of array

4 document.write("Element popped: "+ newstring);

5 document.write("<br>New array: "+ names + "</b>");

</script>

</body>

</html>


The Array() constructor creates a new array called names and intializes the array with four values: "Tom", "Dan", "Liz", and "Jody".
The contents of the array called names is displayed. The last element of the array is removed. The value removed is returned and assigned to the variable called newstring. The popped value is displayed. The shortened array is displayed. (See Figure 9.7.)

The Array() constructor creates a new array called names and intializes the array with four values: "Tom", "Dan", "Liz", and "Jody".

The contents of the array called names is displayed.
The last element of the array is removed. The value removed is returned and assigned to the variable called newstring.
The popped value is displayed.
The shortened array is displayed. (See Figure 9.7.)