Microsoft® JScript®
@set Statement
 Language Reference 
Version 3 

See Also

Creates variables used with conditional compilation statements.
@set @varname = term

The @set statement syntax has these parts:

Part Description
varname Valid JScript variable name. Must be preceded by an "@" character at all times.
term Zero or more unary operators followed by a constant, conditional compilation variable, or parenthesized expression.

Numeric and Boolean variables are supported for conditional compilation. Strings are not. Variables created using @set are generally used in conditional compilation statements, but can be used anywhere in JScript code.

Examples of variable declarations look like this:

@set @myvar1 = 12
@set @myvar2 = (@myvar1 * 20)
@set @myvar3 = @_jscript_version
The following operators are supported in parenthesized expressions: If a variable is used before it has been defined, its value is NaN. NaN can be checked for using the @if statement:
@if (@newVar != @newVar)
This works because NaN is the only value not equal to itself.