how to merge an array of objects to an array of objects contain object an array

Try this:

    let input = [{name: 'x', data: 2},{name: 'y', data: 5},{name: 'x', data: 4},{name: 'y', data: 3}];
    let out = [...new Set(input.map(i => i.name))].map(i => {
        return {name: i, data: input.filter(j => j.name === i).reduce((a,b)=> [a.data].concat([b.data])) };
    });
    console.log(out);

Here's my solution:

const output = input.reduce((previous, next, currentIndex, array) => {
  const index = previous.findIndex((item) => item.name === next.name);
  if (index >= 0) {
    previous[index].data.push(next.data);
  } else {
    previous.push({ ...next, data: [next.data] });
  }
  return previous;
}, []);

You can accomplish this by generating a new array. Simply iterate through the input array and start accumulating the data values of every unique name field into the new merged array. The code would look something like this:

function merge(input){
    let merged = [];
    for (let i=0; i<input.length;i++) {
        let found = merged.findIndex(e => e.name === input[i].name);
        if (found === -1) {
             merged.push({ name: input[i].name, data: [ input[i].data ] });
        } else {
             merged[found].data.push(input[i].data);
        }
    }
    return merged;
}