VBScript in a Nutshell

Error Handling

Error handling does not involve finding errors in your scripts. Instead, use error handling techniques to allow your program to continue executing even though a potentially fatal error has occurred. Ordinarily, all runtime errors that are generated by the VBScript engine are fatal, since execution of the current script is halted when the error occurs. Error handling allows you to inform the user of the problem and either halt execution of the program or, if it is prudent, continue executing the program.

The On Error Resume Next Statement

There are two main elements to error handling in VBScript. The first is the On Error statement, which informs the VBScript engine of your intention to handle errors yourself, rather than to allow the VBScript engine to display a typically uninformative error message and halt the program. This is done by inserting a statement like the following at the start of a procedure:

On Error Resume Next

This tells the VBScript engine that, should an error occur, you want it to continue executing the program starting with the line of code which directly follows the line in which the error occurred. For example, in the simple WSH script:

On Error Resume Next
x = 10
y = 0
z = x / y
Alert z

a “Cannot divide by Zero” error is generated on the fourth line of code because the value of y is 0. But because you’ve placed the On Error statement in line 1, program execution continues with line 5. The problem with this is that when an error is generated, the ...