JSON logical expression parser

main.js

condition = ["OR", ["AND",{field : 'field1', value : 'value2'},{field : 'field2', value : 'value2'}], {field : 'field2', value : 'value1'}];
item = {obj:{'field1' : 'value1','field2' : 'value2'}};


console.log(validateCondition(condition,item));

function validateCondition(condition, item){
       if(!Array.isArray(condition)){
           return assertEquals(condition,item);
       }
       var res = false;
       var logicalOperator = condition[0];
       for (var i = 1; i < condition.length; i++) {

            var loopRes = validateCondition(condition[i], item);
            if(logicalOperator === 'AND'){
                res = (i != 1) ? loopRes && res : loopRes;
            }

            if(logicalOperator === 'OR'){
              res = (i != 1) ? loopRes || res : loopRes;
            }
       }

       return res;
   }

   //fieldAndValueObj = {field : 'fieldName' , value : 'expectedValue'}
   function assertEquals(fieldAndValueObj, item){
       var field = fieldAndValueObj.field;
       var expectedValue = fieldAndValueObj.value;
       if(!(field in item.obj)){
           throw "The field "+field+" is not in the item";
       }
       var realValue = item.obj[field];
       return expectedValue === realValue;
   }