if
One of two values, chosen by a condition: if(condition, a, b) is a when the condition holds and b when it does not. An expression, so it can stand in <params>, <calc>, {{ }} and inside arithmetic; only the chosen value is worked out. (A whole block of statements is the if (condition) { ... } else { ... } statement.)
condition(expression) -- true/false, or a number (not 0 is true)a(any) -- the value when it holdsb(any) -- the value when it does not