[Javascript] Advanced Reduce: Common Mistakes

Take away:

• Always check you ruturn the accumulator
• Always pass in the inital value

 

var data = ["vote1", "vote2", "vote1", "vote2"];

var reducer = function(acc, value){
   if(acc[value]){
     acc[value] = acc[value] + 1;
   }else{
     acc[value] = 1;
   }
  
  return acc;
};

var res = data.reduce(reducer ,{});

console.log(res);