Developing Web Applications
Developing Web Applications |
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Most scripting run-time errors can be attributed to misspelled variables. VBScript automatically declares unrecognized variables, which can lead to subtle errors in your code. To avoid this problem, use the Option Explicit statement as the first line of script on every page. The Option Explicit statement requires variables to be explicitly declared with a Dim statement.
JScript has no counterpart to the Option Explicit statement. Unrecognized variables are automatically declared when they are defined. Some ASP methods, such as Response.Write, produce script errors when used with an undeclared variable. If a variable is declared, but not defined, it will return as either “Undefined” or “NaN.” (For more information, see the JScript documentation.)