Some Predefined Objects (with methods and properties)

        A. window object

        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.
        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
        1. write (str)  writes the string to the HTML document rather than
                        to the window itself.
        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
        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.
        1. length       contains a number representing the number of documents
                        that have previously been loaded into the window.

        D. Form
        1. submit()     submit the form to the specified CGI program.
        2. reset()      resets the form's elements to their original states
        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.
        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 
	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"	
	1. length

	G. Date		New Date objects can be created with Date() constructor
			as in:	var d=new Date();
	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
	Various properties for each Form element type
	1. button:	name
	2. checkbox	checked (boolean)
	3. radio button checked (boolean)
	4. reset	name
	5. select (pull-down menu)
	6. text		name
	7. Text Area	name

	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 
	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
	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

	1. E		the base of natural log
	2. PI		the ratio of a circle's circumsference to its

	K. String	This object is created automatically for each string.
			It is not a property of any object.
	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
	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)