Evaluating the Condition Expression
In all instances, the Condition attribute's value is an expression that evaluates to either True or False. Leaving the attribute value blank equates to setting it to True. Expressions should be in JavaScript or intrinsic function syntax.
Tokens of all kinds may be included in expressions.
Expressions used in Conditions do not require the leading "=" sign which is typically used before formulae in other types of attributes. Values are generally compared using a comparison operator and, when expressions use string or ambiguous data types, both sides of the equation should be enclosed in double-quotes. More complex expressions can be created using logical operators and parentheses.
Here are some example expressions:
| Expression | Comment |
|---|---|
"@Data.LastName~" = "Smith" | Both sides of the equation are known to be strings. |
@Data.CustomerID~ <> 1234 | Both sides of the equation are known to be numbers. |
1 = 1 | This expression can be used to force a True value. |
("@Request.Page~" = "") Or ("@Request.Page~" = "1") | Logical operators can be used. |
InStr("@Data.Categories~", "1") > 0 | Script functions are supported. |
"@Cookie.UserCategory~" = "1" | Cookies are evaluated as text. |
| "@Data.City~" = "Toronto" | When used with the Condition Filter element, causes all datalayer rows where the City column value is not "Toronto" to be removed. |
Complete information about
Built in Functions and Operators
is available for your reference.
Generally, if the expression contains an error of some kind, such as a data type mismatch or a missing function argument, no error message is displayed in the browser; instead, the Condition just doesn't work as desired. However, an error message will usually be included in the Debugger Trace Page (see Debug Reports) at the point at which the expression is evaluated. So, if your Condition isn't working as you expected, check the Debugger page.