javascript - 如何合并对象数组只保留第一个数组中的属性

Question

我有一个工作函数，它通过属性 a1 和 a1 合并两个对象数组。该解决方案基于对一些类似问题的回答，但我的要求是仅保留原始数组 a1 中的属性。

如何调整此函数以返回仅包含第一个数组中的属性的对象数组？

这是一个带有示例数据的 JS fiddle。请注意，输出记录到控制台。另请注意，解决方案必须使用 vanilla Javascript ES6。

https://jsfiddle.net/dba9r3sf/

const a1 = [
 {
    FirstName: "John",
    LastName: "Doe",
    Age: 33,
    Username: "jdoe"
  },
  {
    FirstName: "Mary",
    LastName: "Bloom",
    Age: 63,
    Username: "mbloom"
  },
  {
    FirstName: "Alex",
    LastName: "Arias",
    Age: 21,
    Username: "aarias"
  }
];

const a2 = [
 {
    FirstName: "Johnathan",
    LastName: "Doe",
    Age: 34,
    Username: "jdoe",
    Job: "Graphic Designer"
  },
  {
    FirstName: "Mary-Anne",
    LastName: "Bloom",
    Age: 64,
    Username: "mbloom",
    Job: "Investor"
  },
  {
    FirstName: "Alex",
    LastName: "Arias",
    Age: 22,
    Username: "aarias",
    Job: "Student"
  }
];

/**
   * Merge an array of objects by property
   * @param {array} a1 array 1 destination to be merged into
   * @param {array} a2 array 2 source to be merged, overwrites existing values in a1
   * @param {string} prop name of property to match for merge
   * TODO: Set properties that exist on a1 only otherwise ignore
   */
function mergeByProperty(a1, a2, prop) {

    let merged = [];

    for (let i = 0; i < a1.length; i++) {
      merged.push({
        ...a1[i],
        ...(a2.find((itmInner) => itmInner[prop] === a1[i][prop]))
      });
    }

    return merged;
}

let result = mergeByProperty(a1, a2, 'Username');
console.log(JSON.stringify(result));

// Output:
[{"FirstName":"Johnathan","LastName":"Doe","Age":34,"Username":"jdoe","Job":"Graphic Designer"},{"FirstName":"Mary-Anne","LastName":"Bloom","Age":64,"Username":"mbloom","Job":"Investor"},{"FirstName":"Alex","LastName":"Arias","Age":22,"Username":"aarias","Job":"Student"}]

// Desired output (no "Job" property because that does not exist in the first array of objects):
[{"FirstName":"Johnathan","LastName":"Doe","Age":34,"Username":"jdoe"},{"FirstName":"Mary-Anne","LastName":"Bloom","Age":64,"Username":"mbloom},{"FirstName":"Alex","LastName":"Arias","Age":22,"Username":"aarias"}]

Answer 1

您可以从第一个数组中获取键，然后从第二个数组中选择相应的键/值对

const a1 = [{FirstName: "John",LastName: "Doe",Age: 33,Username: "jdoe"},{FirstName: "Mary",LastName: "Bloom",Age: 63,Username: "mbloom"},{FirstName: "Alex",LastName: "Arias",Age: 21,Username: "aarias"}];
const a2 = [{FirstName: "Johnathan",LastName: "Doe",Age: 34,Username: "jdoe",Job: "Graphic Designer"},{FirstName: "Mary-Anne",LastName: "Bloom",Age: 64,Username: "mbloom",Job: "Investor"},{FirstName: "Alex",LastName: "Arias",Age: 22,Username: "aarias",Job: "Student"}];

function mergeByProperty(a1, a2, prop) {
    let merged = [];
    for (let i = 0; i < a1.length; i++) {
      let found = a2.find((itmInner) => itmInner[prop] === a1[i][prop])
      if(found){
        found = Object.keys(a1[0]).reduce((op,inp)=>{
          op[inp] = found[inp]
          return op
        },{})
      }
      merged.push({
        ...a1[i],
        ...found
      });
    }
    return merged;
}

let result = mergeByProperty(a1, a2, 'Username');
console.log((result));