Instead of copying and shifting values, move back to a non-destructive FOR loop.

Author: jwadhams

logic.js

@@ -125,24 +125,18 @@ jsonLogic.apply = function(logic, data){
 			if( 0 ){ 1 }else if( 2 ){ 3 }else if( 4 ){ 5 }else{ 6 };
 
 			The implementation is:
-			given two+ parameters, 
-				shift off the first two values. 
+			For pairs of values (0,1 then 2,3 then 4,5 etc)
 				If the first evaluates truthy, evaluate and return the second
-				If the first evaluates falsy, start again with the remaining parameters.
-			given one parameter, evaluate and return it.
-			given 0 parameters, return NULL
+				If the first evaluates falsy, jump to the next pair (e.g, 0,1 to 2,3)
+			given one parameter, evaluate and return it. (it's an Else and all the If/ElseIf were false)
+			given 0 parameters, return NULL (not great practice, but there was no Else)
 		*/
-		var v = values.slice(0); //Don't shift values off the original rule, destroy a copy
-		while(v.length >= 2){
-			var conditional = jsonLogic.apply(v.shift(), data),
-				consequent = v.shift();
-
-			if( jsonLogic.truthy(conditional) ){
-				return jsonLogic.apply(consequent, data);
+		for(var i = 0 ; i < values.length - 1 ; i += 2){
+			if( jsonLogic.truthy( jsonLogic.apply(values[i], data) ) ){
+				return jsonLogic.apply(values[i+1], data);
 			}
 		}
-
-		if(v.length === 1) return jsonLogic.apply(v[0], data);
+		if(values.length === i+1) return jsonLogic.apply(values[i], data);
 		return null;
 	}
 

tests/tests.json

@@ -63,7 +63,6 @@
 [{"if":[true, "apple", true, "banana", true, "carrot", "date"]}, null, "apple"],
 
 "Missing",
-
 [{"missing":[]}, null, []],
 [{"missing":["a"]}, null, ["a"]],
 [{"missing":"a"}, null, ["a"]],
@@ -81,7 +80,7 @@
 [{"missing":["a.b"]}, {"a":{"b":"apple brownie"}}, []],
 [{"missing":["a.b", "a.c"]}, {"a":{"b":"apple brownie"}}, ["a.c"]],
 
-"Missing and If are friends",
+"Missing and If are friends, because empty arrays are falsey in JsonLogic",
 [{"if":[ {"missing":"a"}, "missed it", "found it" ]}, {"a":"apple"}, "found it"],
 [{"if":[ {"missing":"a"}, "missed it", "found it" ]}, {"b":"banana"}, "missed it"],
 
@@ -98,23 +97,17 @@
 [{"merge":[1,2]}, null, [1,2]],
 [{"merge":[1,[2]]}, null, [1,2]],
 
-"Missing and Merge, and If are friends. VIN is always required, APR is only required if financing is true.",
+"Missing, Merge, and If are friends. VIN is always required, APR is only required if financing is true.",
 [
-{"missing":{"merge":[
-	"vin", 
-	{"if": [{"var":"financing"}, ["apr"], [] ]}
-]} },
-{"financing":true},
-["vin","apr"]
+	{"missing":{"merge":[ "vin", {"if": [{"var":"financing"}, ["apr"], [] ]} ]} },
+	{"financing":true},
+	["vin","apr"] 
 ],
 
 [
-{"missing":{"merge":[
-	"vin", 
-	{"if": [{"var":"financing"}, ["apr"], [] ]}
-]} },
-{"financing":false},
-["vin"]
+	{"missing":{"merge":[ "vin", {"if": [{"var":"financing"}, ["apr"], [] ]} ]} },
+	{"financing":false},
+	["vin"]
 ],
 
 "END"