let arr = [ { a: "xinxin" }, { a: "pipi" }, { a: "zhazha" }, { a: "xinxin", c: 1 }, ]合并相同的key

One way to merge objects with the same key is to use reduce() method along with Object.keys() and Object.values() methods. Here's an example:

let arr = [
  { a: "xinxin" },
  { a: "pipi" },
  { a: "zhazha" },
  { a: "xinxin", c: 1 },
];

let result = arr.reduce((acc, curr) => {
  let key = Object.keys(curr)[0];
  if (acc[key]) {
    acc[key] = Object.assign(acc[key], curr);
  } else {
    acc[key] = curr;
  }
  return acc;
}, {});

console.log(Object.values(result)); // [{a: "xinxin", c: 1}, {a: "pipi"}, {a: "zhazha"}]

In this example, the reduce() method is used to iterate over the array and accumulate the objects with the same key in the `acc` object. The `curr` object is checked for its key (using Object.keys() method) and if a matching key is found in `acc`, the objects are merged (using Object.assign() method) and stored in `acc`. Otherwise, `curr` is stored as is in `acc`. Finally, the `Object.values()` method is used to extract the values from the `result` object and return them as an array.