Merge duplicate objects in array of objects

Question

I have below array of objects,

var data = [
    {
        label: \"Book1\",
        data: \"US edition\"
    },
    {
        label: \"Book1\",
        data:         


        

Answer 1

I came across the same situation and I was hoping to use the Set instead of mine here

const data = [
  {
    label: "Book1",
    data: "US edition"
  },
  {
    label: "Book1",
    data: "UK edition"
  },
  {
    label: "Book2",
    data: "CAN edition"
  },
  {
    label: "Book3",
    data: "CAN edition"
  },
  {
    label: "Book3",
    data: "CANII edition"
  }
];

const filteredArr = data.reduce((acc, current) => {
  const x = acc.find(item => item.label === current.label);
  if (!x) {
    const newCurr = {
      label: current.label,
      data: [current.data]
    }
    return acc.concat([newCurr]);
  } else {
    const currData = x.data.filter(d => d === current.data);
    if (!currData.length) {
      const newData = x.data.push(current.data);
      const newCurr = {
        label: current.label,
        data: newData
      }
      return acc;
    } else {
      return acc;
    }
    
  }
}, []);

console.log(filteredArr);