Multi-line comments begin with "/*" and end with "*/".
// This is a single-line comment
/*
This is
a multi-line
comment.
*/
Dot Notation
In JavaScript, objects can be referenced using dot notation, starting with the
highest-level object (i.e, window). Objects can be referred to by name or id or by
their position on the page.
For example, if there is a form on the page named "loginform", using dot notation
you could refer to the form as follows:
window.document.loginform
Assuming that loginform is the first form on the page, you could also refer to this way:
window.document.forms[0]
A document can have multiple form elements as children. The number in the square
brackets ([]) indicates the specific form in question. In programming speak, every
document object contains an array of forms. The length of the array could be zero
(meaning there are no forms on the page) or greater.
In JavaScript, arrays are zero-based, meaning that the first form on the page is
referenced with the number zero (0) as shown in the syntax example above.
Square Bracket Notation
Objects can also be referenced using square bracket notation as shown below.
window['document']['loginform']
// and
window['document']['forms[0]']
Dot notation and square bracket notation are completely interchangeable. Dot notation
is much more common; however, as we will see later in the course, there are times when
it is more convenient to use square bracket notation.
