A Microsoft JScript code statement consists of one or more items and symbols on a line. A new line begins a new statement, but it is a good idea to terminate your statements explicitly. The semicolon (;) is the termination character.

aBird = "Robin";
var today = new Date();

A group of JScript statements that is surrounded by braces is called a block. Blocks of statements are used, for example, in functions and conditionals. In the following example, the first statement begins the definition of a function, which consists of the block of five statements that follows. The last three statements, which are not surrounded by braces, do not constitute a block and are not part of the function definition.

function convert(inches)  {
    feet = inches / 12;  //  These five statements are in a block.
    miles = feet / 5280;
    nauticalMiles = feet / 6080;
    cm = inches * 2.54;
    meters = inches / 39.37;
}
km = meters / 1000;  //  These three statements are not in a block.
kradius = km;
mradius = miles;

Comments

A single-line JScript comment begins with a pair of forward slashes (//). A multiline comment begins with a forward slash and asterisk in combination (/*), and ends with the reverse (*/).

aGoodIdea = "Comment your code thoroughly.";  //  This is a single-line comment.

/*
This is a multiline comment that explains the preceding code statement.

The statement assigns a value to the aGoodIdea variable. The value, which is contained
between the quote marks, is called a literal. A literal explicitly and directly contains
information, rather than referring to the information indirectly. (The quote marks are not
part of the literal.)
*/

//  This is another multiline comment, written as a series of single-line comments.
//  After the statement is executed, you can refer to the content of the aGoodIdea
//  variable by using its name, as in the next statement, in which a string literal is
//  appended to the aGoodIdea variable by concatenation to create a new variable.

var extendedIdea = aGoodIdea + " You never know when you'll have to figure out what it does.";

JScript Assignments

If you are just beginning to become familiar with programming, please be aware that the equal sign (=) is used in JScript to indicate the action of assigning a value. That is, if a JScript code statement says

anInteger = 3;

it means "Assign the value 3 to the variable anInteger," or "anInteger gets 3." When you need to compare two values to find out whether they are equal, use a pair of equal signs (==). This issue is discussed in detail in conditionals.

Expressions

The term expression, in JScript, is something that a human being can read as a Boolean or numeric expression. Expressions contain symbol characters like "+" rather than words like "added to". Any legal combination of values, variables, operators, and expressions constitutes an expression.

var anExpression = "3 * (4 / 5)";
var aSecondExpression = "Math.PI * radius * 2";
var aThirdExpression = aSecondExpression + "%" + anExpression;
var aFourthExpression = "(" + aSecondExpression + ") % (" + anExpression + ")";

© 1996 by Microsoft Corporation.

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