Conditions and Expressions

Xponent uses Expressions extensively within Business Logic and for Conditional branches in graphs. Each expression can be defined in one of two ways: Basic or Advanced. Both of these techniques generates a JavaScript expression which is evaluated for truthfulness.

Basic Expressions

Basic expressions provide a drop down list of common expressions which are available to be used:

Selecting Advanced from the dropdown shows a JavaScript expression window that allows any valid JavaScript Boolean expression to be entered. By default when switching from the Basic to the Advanced view the equivalent JavaScript will be shown.

Basic Expression	Arguments	Equivalent JavaScript	Note

Basic Expression	Arguments	Equivalent JavaScript	Note
Is True	None	VAL === true
Is False	None	VAL === false
Less Than or Equal To	Constant Value - numeric or string	VAL <= 12.3
Greater Than	Constant Value - numeric or string	VAL > 12.3
Greater Than or Equal To	Constant Value - numeric or string	VAL >= 12.3
Equals	Constant Value - numeric, string or boolean	VAL == {...}
Not Equal To	Constant Value - numeric, string or boolean	VAL != {...}
Contains	Constant String	VAL.indexOf('abc') > -1	This is case sensitive.
Starts With	Constant String	VAL.indexOf("abc") === 0	This is case sensitive. See this Knowledge Base article on how to make it case insensitive.
Ends With	Constant String	VAL.lastIndexOf("abc") === VAL.length - "abc".length	This is case sensitive. See this Knowledge Base article on how to make it case insensitive.

Advanced Expressions

Advanced expressions are any valid boolean JavaScript (ECMAScript 5) expressions. The JavaScript variable 'VAL' is always available and is set to the value of the previous node when used as an expression on a conditional branch.

If the Basic Expressions do not have the type of operator that you require then the advanced mode should allow you to program your own condition. Examples include:

Description	Conditional	JavaScript

Description

Conditional

JavaScript

Membership of a list. Test to see if the returned value is in a list of values.

['worda', 
 'wordb', 
 'wordc'].indexOf(VAL) >= 0

Check if a javascript object is empty or not

Object.keys(obj).length === 0 && obj.constructor === Object

Miscellany

It is worth taking note that JavaScript has some interesting outcomes when comparing against null:

null >= 0 → true
null <= 0 → true
null == 0 → false
+null == 0 → true

Journey Hub

Conditions and Expressions

Basic Expressions

Advanced Expressions

Miscellany

Related pages