Using a Variable for the Selection

A variable is a temporary holder of information, such as the user’s selection in a drop-down box. Using variables clarifies the programming logic, making it easier to troubleshoot. The table below lists the characteristics of a variable.

Characteristic	Explanation
Name	Names must start with a letter or underscore. Subsequent characters may include letters, numbers, or the underscore (drp_Territory is a legal name). A variable name cannot be a reserved word (new is a reserved word, but newVariable is not). Use a JavaScript var statement to declare a variable name before it is used. For example: var newVariable; In the above statement, JavaScript reserves the name newVariable, with a value of null or undefined.
Value	Values are assigned to variables with the JavaScript assignment operator (=). Any type of data can be assigned to a variable: an object (a string, a user selection, an object path), a boolean (true or false), or a number. For example: var newVariable; newVariable=true; The value can be assigned in a separate statement like above, or in the same statement that declares the variable name. For example: var newVariable=true; newVariable (and its value) is available only within the script or function that declares it, preventing accidental changes from other scripts using the same variable name.

Characteristic

Explanation

Name

Names must start with a letter or underscore. Subsequent characters may include letters, numbers, or the underscore (drp_Territory is a legal name). A variable name cannot be a reserved word (new is a reserved word, but newVariable is not).

Use a JavaScript var statement to declare a variable name before it is used. For example:

var newVariable;

In the above statement, JavaScript reserves the name newVariable, with a value of null or undefined.

Value

Values are assigned to variables with the JavaScript assignment operator (=). Any type of data can be assigned to a variable: an object (a string, a user selection, an object path), a boolean (true or false), or a number. For example:

var newVariable;
newVariable=true;

The value can be assigned in a separate statement like above, or in the same statement that declares the variable name. For example:

var newVariable=true;

newVariable (and its value) is available only within the script or function that declares it, preventing accidental changes from other scripts using the same variable name.

This exercise uses a variable to hold the user’s selection (the first line of the script from the preceding exercise). A variable can be declared in one statement and the value assigned in another:

var Selection;
Selection=Territory.Item(Territory.SelectedIndex);

or the statements can be combined:

var Selection=Territory.Item(Territory.SelectedIndex);

Note:

The following exercise continues from the previous section. This exercise alters the script in the drop-down box (renamed drp_Territory) in the Limits Dashboard section of Sample1mod.bqy.