Microsoft® JScript®
Writing JavaScript Code
 JScript Tutorial

Like many other programming languages, Microsoft JavaScript is written in text format, and is organized into statements, blocks consisting of related sets of statements, and comments. Within a statement you can use variables, immediate data such as strings and numbers, and expressions.
A JavaScript 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. You can do this with the semicolon (;), which is the JavaScript termination character.
aBird = "Robin";
var today = new Date();
A group of JavaScript 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 a block of five statements. The last three statements, which are not surrounded by braces, are not 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;
A single-line JavaScript 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; it does not refer 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.";
Assignments and Equality
The equal sign (=) is used in JavaScript to indicate the action of assigning a value. That is, a JavaScript code statement could say
anInteger = 3;
It means "Assign the value 3 to the variable anInteger," or "anInteger takes the value 3." When you want to compare two values to find out whether they are equal, use a pair of equal signs (==). This is discussed in detail in Controlling Program Flow.
A JavaScript expression is something that a person can read as a Boolean or numeric expression. Expressions contain symbol characters like "+" rather than words like "added to". Any valid 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 + ")";

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