如何检查对象数组中两个相等的属性是否同时重复？

Question

我有以下对象数组：

[
 { 
   homeGate: "gate_0",
   homeTerminal: "1",
   destinationGate: "gate_0",
   destinationTerminal: "2"   
 },
 { 
   homeGate: "gate_0",
   homeTerminal: "1",
   destinationGate: "gate_0",
   destinationTerminal: "3"   
 },
 { 
   homeGate: "gate_1",
   homeTerminal: "1",
   destinationGate: "gate_1",
   destinationTerminal: "2"   
 },
 { 
   homeGate: "gate_1",
   homeTerminal: "2",
   destinationGate: "gate_1",
   destinationTerminal: "3"   
 },
]

我需要检查哪些对象同时重复值“homeTerminal”和“destinationTerminal”。正如我们在示例中看到的，我需要同时检索两个属性中具有相同值的第一个和第三个对象。

我尝试制作地图，但我只能使用一个值来完成，而且我不知道如何同时检查两个值。 提前谢谢你。

Answer 1

你可以reduce数组来得到想要的结果。

var arr = [{
  homeGate: "gate_0",
  homeTerminal: "1",
  destinationGate: "gate_0",
  destinationTerminal: "2"
}, {
  homeGate: "gate_0",
  homeTerminal: "3",
  destinationGate: "gate_0",
  destinationTerminal: "2"
}, {
  homeGate: "gate_1",
  homeTerminal: "1",
  destinationGate: "gate_1",
  destinationTerminal: "2"
}, {
  homeGate: "gate_2",
  homeTerminal: "1",
  destinationGate: "gate_2",
  destinationTerminal: "2"
}, {
  homeGate: "gate_1",
  homeTerminal: "2",
  destinationGate: "gate_1",
  destinationTerminal: "3"
}, {
  homeGate: "gate_1",
  homeTerminal: "3",
  destinationGate: "gate_1",
  destinationTerminal: "2"
}]


var result = arr.reduce((retArr, item) => {
  // condition to avoid duplication
  if (!retArr.includes(item)) {
    var filteredArr = arr.filter((i) => {
      return i.homeTerminal === item.homeTerminal && i.destinationTerminal === item.destinationTerminal;
    });
    if (filteredArr.length > 1) retArr = [...retArr, ...filteredArr];
  }
  return retArr;
}, []);

console.log(result);

数组原型的reduce方法有2个参数：

1. 为数组的每个元素执行的回调函数。
2. 返回值的初始值
   1. 此值必须从回调函数返回

回调函数依次接受 3 个参数：

1. return_value (retArr)
2. 数组元素 (item)
3. 索引未使用

可以对数组元素进行任何操作，结果必须反映在 return_value 中（此处为展开值的接触操作）

更多关于reducehttps://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce

Answer 2

var arr=[
 { 
   homeGate: "gate_0",
   homeTerminal: "1",
   destinationGate: "gate_0",
   destinationTerminal: "2"   
 },
 { 
   homeGate: "gate_0",
   homeTerminal: "1",
   destinationGate: "gate_0",
   destinationTerminal: "3"   
 },
 { 
   homeGate: "gate_1",
   homeTerminal: "1",
   destinationGate: "gate_1",
   destinationTerminal: "2"   
 },
 { 
   homeGate: "gate_1",
   homeTerminal: "2",
   destinationGate: "gate_1",
   destinationTerminal: "3"   
 },
]


var r=[];
    arr.forEach((element,index) => {
        for(let i=index;i<arr.length;i++){
            if(element.homeTerminal==arr[i].homeTerminal&&element.destinationGate==arr[i].destinationGate){
                if(!r.includes(element))r.push(element);
                if(!r.includes(arr[i]))r.push(arr[i]);
            }
        }
    });

应该可以。你在 r 数组中得到结果

Answer 3

您可以使用由字段 homeTerminal 和 destinationTerminal 组成的复合键来计算查找/映射。

然后使用该查找来查找重复元素。

const lkp = data.reduce((lkp, cur) => {
    const {homeTerminal, destinationTerminal} = cur;
    const key = `${homeTerminal}~~${destinationTerminal}`;

    lkp[key] = lkp[key] || [];

    lkp[key].push(cur);

    return lkp;
}, {});

console.log (lkp);

for (const key in lkp) {
    if (lkp[key].length > 1) 
        console.log ("Duplicate entry", lkp[key])
}

<script>var data = [
 { 
   homeGate: "gate_0",
   homeTerminal: "1",
   destinationGate: "gate_0",
   destinationTerminal: "2"   
 },
 { 
   homeGate: "gate_0",
   homeTerminal: "1",
   destinationGate: "gate_0",
   destinationTerminal: "3"   
 },
 { 
   homeGate: "gate_1",
   homeTerminal: "1",
   destinationGate: "gate_1",
   destinationTerminal: "2"   
 },
 { 
   homeGate: "gate_1",
   homeTerminal: "2",
   destinationGate: "gate_1",
   destinationTerminal: "3"   
 },
]</script>