Question

我有2个阵列

var a = [{id: 1, name:"SFO"}, {id:2, name:"ATL"}];

var b = [{number: 1, sourceId:1, destinationId:2}, {number:2, sourceId:2, destinationId:1}];

我想以这种形式返回一个数组：

[{source: {name: "SFO"}, destination: {name: "ATL"}}, {source: {name:"ATL"}, destination: {name: "SFO"}}]

如何使用filter和reduce来生成上面的结果

Answer 1

获得预期数组的代码：

var a = [{id: 1, name:"SFO"}, {id:2, name:"ATL"}];
var b = [{number: 1, sourceId:1, destinationId:2}, {number:2, sourceId:2,  destinationId:1}];

var arr = [];
for(var i=0; i<b.length; i++){
    arr.push({
        source: {name: findName(b[i].sourceId, a) },
        destination: {name: findName(b[i].destinationId, a) }
    });
}

function findName(nr, a){
    for(var i=0; i<a.length; i++){
        if(nr==a[i].id){
            return a[i].name;
        }
    }
}

//[{source: {name: "SFO"}, destination: {name: "ATL"}}, {source: {name:"ATL"}, destination: {name: "SFO"}}]
console.log(arr);

使用地图和过滤器获得预期的数组：

var a = [{id: 1, name:"SFO"}, {id:2, name:"ATL"}];
var b = [{number: 1, sourceId:1, destinationId:2}, {number:2, sourceId:2, destinationId:1}];

var arr = b.map(function(obj){
    return {
        source: { name: a.filter(function(obj2){ if(obj2.id==obj.sourceId) return obj2.name; })[0].name },
        destination: { name: a.filter(function(obj2){ if(obj2.id==obj.destinationId) return obj2.name; })[0].name }
    };
});

//[{source: {name: "SFO"}, destination: {name: "ATL"}}, {source: {name:"ATL"}, destination: {name: "SFO"}}]
console.log(arr);

Answer 2

如果必须这样做，可以使用map()和find()，但效率非常低，您应该更改数据结构。

＆＃13;

var a = [{id: 1, name:"SFO"}, {id:2, name:"ATL"}];
var b = [{number: 1, sourceId:1, destinationId:2}, {number:2, sourceId:2, destinationId:1}];


var result = a.map(function(e) {
  var o = {}
  o.source = {
    name: e.name
  }
  var destB = b.find(function(f) {
    return e.id == f.sourceId
  })
  if (destB) {
    destB = destB.destinationId
    var destName = a.find(function(x) {
      return x.id == destB
    })
    if (destName) {
      destName = destName.name;
      o.destination = {
        name: destName
      }
    }
  }
  return o
})

console.log(result)

＆＃13;

如何在javascript中组合过滤和减少数组

2 个答案: