Some Predefined Objects (with methods and properties)
A. window object
methods.
1. alert (str): displays an alert D.B. containing the string argument
as text.
2. setInterval (function,time)
causes the function to be repetatively called
at regular time intervals in milliseconds.
3. clearInterval (name)
clears a setInterval() call where the argument, name,
represents a certain setInterval() call.
4. confirm(str):displays a confirm D.B. containing the string argument
as text. you need either OK(confirm) or cancel.
returns a boolean value.
5. prompt (str,str)
displays a prompt D.B. containing the first argument
string as an instruction on what to enter.
The second argument is the default to be returned
in case the user does not enter a string.
properties.
1. closed contains a boolean value corresponding to whether or not
the window is closed.
2. document an object itself
3. history an object itself
4. location contains the URL of the document currently displayed
in the window.
can be changed to cause a new document to be displayed.
B. document object: a property of the window object
methods:
1. write (str) writes the string to the HTML document rather than
to the window itself.
properties:
1. linkColor contains the color of unvisited links
2. alinkColor contains the color of active link.
3. vlinkColor contains the color of visited links.
4. bgColor contains the color of background
5. fgColor contains the color of foreground
6. Form an object itself
7. Image[] an object itself
8. lastModified contains the date the document was last changed.
C. history: a property of the window object
methods:
1. back() Causes the same effect as hitting the back button of
the browser.
2. forward() causes the same effect as hitting the foreward button
3. go(-num) causes the window to display a document back in its
history list.
property:
1. length contains a number representing the number of documents
that have previously been loaded into the window.
D. Form
methods:
1. submit() submit the form to the specified CGI program.
2. reset() resets the form's elements to their original states
property:
1. elements[] an object itself
E. Image[] a property of the document object.
This array is automatically created to index all of
images that have been marked up with the HTML IMG tags.
A new image can be constructed with the Image()
constructor to preload it.
properties:
1. src contains the image's source URL
2. border contains the image's border setting in pixels
3. height contains the image's height in pixels
4. width contains the image's width in pixels
5. name can be set with the NAME attribute of the HTML IMG tag.
can be declared when a new image is constructed with
Image() constructor.
F. Array New arrays can be created with the Array() constructor.
Ex: var list_1 = new Array(100); // 100-elements
var list_2 = new Array (10,20, "what"); // 3-elements
list_3 = Array [10,20, "what"]; // same as list_2
A two-dimensional array is an array of arrays, each
one-dimensional
methods
1. list_2.sort() results in ["10", "20", "what"]
2. list_2.join() results in "10, 20, what"
3. list_2.reverse results in ["what", 20, 10]
4. list_2.slice(1) results in [20, "what"]
5. list_2.push("next") results in [10, 20, "what", "next"]
6. list_2.pop results in "what"
property
1. length
G. Date New Date objects can be created with Date() constructor
as in: var d=new Date();
methods
1. getDate() returns the day of the month (1-31)
2. getDay() returns the day of the week (1-7)
3. getHours() returns the hours (0-23)
4. getMonth (1-12)
5. getSeconds() (0-59)
6. getYear() returns the year.
H. elements[] This object is a property of a Form object that
contains. It is created automatically when the
HTML document is loaded that contains a Form
element.
Various properties for each Form element type
1. button: name
value
2. checkbox checked (boolean)
name
value
3. radio button checked (boolean)
name
value
4. reset name
value
5. select (pull-down menu)
name
options[]
selectedIndex
value
6. text name
value
7. Text Area name
value
I. options[] This object is a property of SELECT menu.
It indexes all of a pull-down menu options.
Each option has the following properties
1. index The index number of a particular option
2. text contains the text string that appears on
the menu for that option
3. value can carry a hidden value for that option.
J. Math A new Math object does not have to be created
to call upon the properties or methods
methods
1. random() returns a floating-point number 0.0 - 0.999999
takes no argument.
2. pow(base,expo) raises the given base to the power of the second
argument.
3. max(num1,num2)
4. min(num1,num2)
5. round(num) returns its argument rounded to the nearest integer.
6. floor(num) returns greatest integer less than its argument
7. ceil(num) returns the least integer greater than its argu.
8. abs(num) returns the absolute value
9. exp(num) returns e to the power of the argument
properties
1. E the base of natural log
2. PI the ratio of a circle's circumsference to its
diameter
K. String This object is created automatically for each string.
It is not a property of any object.
methods
1. charAt(ind) returns the character in the string at given ind
2. charCodeAt(ind) returns the ASCII number for the character at
specified index of the string.
3. indexOf(char) returns the first index of the given character
returns -1 if no such character
4. lastIndexOf(char)
returns the last index at which the char is found.
-1 is returned if not found.
5. substring(ind)
returns a substring starting from the given index.
6. toLowerCase()
7. toUpperCase()
L. Global This is not a property of any object.
Nor does it have to be referenced to call its methods
We simply call the methods by name
methods
1. parseInt(str,num)
returns the string converted to an integer in the
base given by the second argument.
If the second argument is omitted, the default is 10.
2. parseFloat(str) returns the string converted to a floating-
point number. (decimal)