Each Form object contains an elements[] array that stores a reference to each input element (radio button, checkbox, textarea, etc.) within a form. Like any array, the elements[] array includes a length property that references the number of elements in a form. You can refer to input elements using this array, or you can refer to specific elements by name:

document.formName.elementName

If multiple elements share the same name, as is the case with radio buttons and checkboxes, each element is stored as part of a named array. For instance, in a form named formOne containing a set of radio buttons named "age", you can refer to each individual radio button through its index number:

document.formOne.age[0] // first radio button
document.formOne.age[1] // second radio button

document.formOne.text1.value = "new text input value";
var textVal = document.formOne.textarea1.value;

For radio buttons and checkboxes, the value property only stores the value to be transmitted to the server, and does not indicate whether or not an element is selected. To verify this, use the checked property, which has a value of true (if selected) or false (if not selected).

// returns an array index number for the selected option
document.formOne.select1.selectedIndex;
// the value of option number i
document.formOne.select1.options[i].value;

• Loop through form elements
• Designating optional elements
• Check elements by type
  Includes validation of text, textarea, select menus, and a secondary function to validate radio buttons.
• Validating string length
  This example checks for all values and verifies that the zip code is exactly 5 digits. (Look for the length property of the zip code field in the source code).

// in milliseconds
new Date(ms)

// as a string
new Date("Wed, 6 June 2001 20:00:00")

//as a set of individual arguments
new Date(year, month, day, hours, minutes, seconds, ms)

Note that when passing arguments to the Date constructor, you must specify the month using its index, where January = 0, February =1 and so on. The year and month arguments are required, but the others are optional and may be omitted.

• getDate() - returns the date (0-31) of a Date object.
• getDay() - returns the day (0-6) of a Date object.
• getFullYear() - returns the 4 digit year.
• getHours() - returns the hour (0-23).
• getMilliseconds() - returns milliseconds of a Date object.
• getMinutes() - returns the minutes (0-59).
• getMonth() - returns the month (0-11).
• getSeconds() - returns the seconds (0-59).
• getTime() - converts a date and time to a millisecond representation. see Date.parse()
• getTimezoneOffset() - returns the difference between local time and GMT in minutes.

• setDate() - sets the date (0-31) of a Date object.
• setFullYear() - sets the 4 digit year.
• setHours() - sets the hour (0-23).
• setMilliseconds() - sets the milliseconds field.
• setMinutes() - sets the minutes (0-59).
• setMonth() - set the month field (0-11).
• setSeconds() - sets the seconds(0-59).

• toString() - converts a date to a string.
• toUTCString() - converts a date to a string, expressed in universal time.
• Date.parse() - converts a date and time to a millisecond representation. Always used with the global Date object rather than a custom Date object.

You can write new cookie data and retrieve data that you have set using JavaScript's document.cookie property. This property contains a string of name=value pairs separated by semi-colons. For instance, if you have set multiple cookies, each with one name=value pair, reading the document.cookie property produces a string of all of these cookies values:

login=Carrie; zip=94122

Note that when reading cookies, you only have access to cookies set from your own server or domain name.

document.cookie="login=Scully";

// set the value to a user input variable
document.cookie="login=" + username;

In addition to name=value pairs, cookies can contain 4 optional attributes: expires, path, domain, and secure. If you do not set the expires attribute to a specific date, the cookie expires when the user ends the browsing session. When setting an expiration date, the date should be formatted using the Date.toGMTString() method.

// grab the current date
var myExpire = new Date();

// set the month to 6 months in the future
myExpire.setMonth(myExpire.getMonth() + 6);

//set the date to a GMT string format
myExpire.toGMTString();

//add the expires attribute to the cookie
document.cookie="login=" + username + "; expires=" + myExpire;

By default, cookies are accessible to the directory in which they were set and any subdirectories. To make a cookie accessible to other directories on the same server, use the path attribute. Setting the path attribute to "/" makes the cookie accessible to all directories on the server.

document.cookie="login=" + username + "; expires=" + myExpire + "; path=/";

Similarly, if you want to have a cookie be accessible to multiple subdomains, use the domain attribute.

• String.indexOf(substring) This method searches a string for an occurrence of a substring that you specify. The value returned is a number that indicates the position of the first character of the substring. If the substring is not located, the return value is -1.

• String.indexOf(substring, start) Searches a string for a substring, but rather than searching from the beginning of the string, it searches from the start position you indicate. The value of this argument must be a number between 0 and the total number of characters in the string.

• String.substring(start, end) Returns a portion of a larger string, defined by the position of the first character (start) and the position of the last character (end). The substring includes the start character but not the end character.

// search for the name of the cookie, 'login'
var initialPosition = document.cookie.indexOf("login=");

/* only continue if it finds the cookie name. If there is no cookie by that name, the value of the variable is -1 */
if (initialPosition != -1) {

//define the char position of the value
start = initialPosition + 6;

//define the char position of the end of the value
end = document.cookie.indexOf(";",start)

/* if it can't find a terminal semi-colon, set the end value to the end of the entire cookie */
if (end == -1) end = document.cookie.length;

//extract the value using the start and end positions
var userLogin = document.cookie.substring(start,end);
}