Question

有两个数组：

[
  {"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 1},
  {"id": "344430b94t4t34rwefewfdff", "quantity": 5},
  {"id": "342343343t4t34rwefewfd53", "quantity": 3}
]

和

[
  {"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 2},
  {"id": "344430b94t4t34rwefewfdff", "quantity": 1}
]

如何将它们合并为一个求和数量？

[
  {"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 3},
  {"id": "344430b94t4t34rwefewfdff", "quantity": 6},
  {"id": "342343343t4t34rwefewfd53", "quantity": 3}
]

其中之一有时可能是空的

Answer 1

您可以使用普通的JavaScript来实现。

使用Array.reduce()通过id制作一个中间字典并累加数量，然后用Object.values()将其变成一个数组：

const arr1 = [
  {"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 1},
  {"id": "344430b94t4t34rwefewfdff", "quantity": 5},
  {"id": "342343343t4t34rwefewfd53", "quantity": 3}
];
const arr2 = [
  {"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 2},
  {"id": "344430b94t4t34rwefewfdff", "quantity": 1}
];

const result = Object.values([...arr1, ...arr2].reduce((acc, { id, quantity }) => {
  acc[id] = { id, quantity: (acc[id] ? acc[id].quantity : 0) + quantity  };
  return acc;
}, {}));

console.log(result);

Answer 2

您可以使用lodash，但是现代香草JS既可行又高效。我想其他答案将使用类似reduce之类的功能性方法，所以这是一个使用带有find的简单for/of循环而不是可能更长的字典查找的版本，但是比较容易理解。

const arr1 = [{"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 1}, {"id": "344430b94t4t34rwefewfdff", "quantity": 5}, {"id": "342343343t4t34rwefewfd53", "quantity": 3}];
const arr2 = [{"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 2}, {"id": "344430b94t4t34rwefewfdff", "quantity": 1}];

function merge(arr1, arr2) {

  // Merge the arrays, and set up an output array.
  const merged = [...arr1, ...arr2];
  const out = [];

  // Loop over the merged array
  for (let obj of merged) {

    // Destructure the object in the current iteration to get
    // its id and quantity values
    const { id, quantity } = obj;

    // Find the object in out that has the same id
    const found = out.find(obj => obj.id === id);

    // If an object *is* found add this object's quantity to it...
    if (found) {
      found.quantity += quantity;

    // ...otherwise push a copy of the object to out
    } else {
      out.push({ ...obj });
    }
  }
  
  return out;

}

console.log(merge(arr1, arr2));

Answer 3

您可以通过reduce来做到这一点：

let a1 = [
  {"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 2},
  {"id": "344430b94t4t34rwefewfdff", "quantity": 1}
];

let a2 = [
  {"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 1},
  {"id": "344430b94t4t34rwefewfdff", "quantity": 5},
  {"id": "342343343t4t34rwefewfd53", "quantity": 3}
];

let result = Object.values(a1.concat(a2).reduce((acc, v) => {
   if (!acc[v.id]) {
       acc[v.id] = {id: v.id, quantity: 0};
   }
   acc[v.id].quantity += v.quantity;
   return acc;
}, {}));

console.log("Results: ", result);

Answer 4

带有附加对象键的版本。函数的主体不会干扰具有属性的对象。因此，以“数量”求和，然后以“ prop”检查

var first = [ 
  {quantity:100, id:1, variantId: 1}, 
  {quantity:300, id:2, variantId: 2, propA: 'aaa'},

];

var second = [
  {quantity:100, id:1, variantId: 1},
  {quantity:200, id:2, variantId: 2, propB: true}, 
  {quantity:300, id:3, variantId: 3, propC: 'ccc'}, 
]

function mergeArrays(arrayOfArrays, propToCheck, propToSum) {
    let sum = [];
    [].concat(...arrayOfArrays).map(function(o) {
        
        let existing = sum.filter(function(i) { return i[propToCheck] === o[propToCheck] })[0];
    
        if (!existing) {

            sum.push(o);
        } else {

            existing[propToSum] += o[propToSum];
            
            let copyProps = Object.keys(o).filter(obj => {
                  return existing[obj] !== o[obj]
            }).map(val => (val !== propToSum) ? existing[val] = o[val] : null)
        }
             
    });

    return sum;
}

console.log(mergeArrays([first, second], 'variantId', 'quantity'))

Answer 5

您可以使用.reduce和.find方法来实现。

const arr1 = [{"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 1}, {"id": "344430b94t4t34rwefewfdff", "quantity": 5}, {"id": "342343343t4t34rwefewfd53", "quantity": 3}];
const arr2 = [{"id": "5c5030b9a1ccb11fe8c321f4", "quantity": 2}, {"id": "344430b94t4t34rwefewfdff", "quantity": 1}];

const result =  [...arr1, ...arr2].reduce((accumulator, currentValue) => {
  const element = accumulator.find(item => item.id === currentValue.id)
  element ? element.quantity += currentValue.quantity : accumulator.push(currentValue)
  return accumulator
},[])

console.log(result)

Answer 6

所有这些答案都要求您知道要选择和求和的对象结构。

lodash 实际上允许您在不知道结构的情况下执行此操作；通过使用 customizer 的 _.mergeWidth 参数；

let result = _.mergeWith(arr1, arr2, (objValue, srcValue, key, object, source, stack) =>{
    
    //Add any conditions you need here. Ive added a few relevant examples. 
    //if(key.startsWith("num")) //Check for property name prefixes like num...
    //if(propertyNamesToSum.Includes(key)) //check if your property is in your predefined list of property names
    //This one below sums any properties that are numbers
    if(_.isNumber(srcValue) && _.isNumber(objValue)){
        return srcValue + objValue;
    } 
    return undefined; //lodash will merge as usual if you return undefined. 

});

Lodash 文档 - https://lodash.com/docs/4.17.15#mergeWith

如何使用lodash合并两个数组并求和重复对象的值

6 个答案: