anObject = {'a': 'apple', 'b': 'banana'};
largeArray = ['a','c','d'];
emptyArray = [];

for(var s = 0; s < largeArray.length; s++){
        if(anObject[largeArray[s]]){
          emptyArray.push(anObject[largeArray[s]]);
        }
      }

emptyArray = ['a']