过滤器数组属性打字稿

Question

我有2个array：

  items = [
    {
      offenceType:"7",
      offenceCode:"JLN14",
    }, 
    {
      offenceType:"48",
      offenceCode:"JLN14",
    }
  ];



  demo = [
    {
      offenceCode: 'JLN14',
      offenceType: '7',
      offenceDesc: 'emergency lane abuse'
    },
    {
      offenceCode: 'JLN14',
      offenceType: '48',
      offenceDesc: 'speeding'
    },
    {
      offenceCode: 'JLN13',
      offenceType: '52',
      offenceDesc: 'parking abuse'
    }
  ];

如何在这2个array之间过滤一些属性，例如： 在items中得到了offenceType和OffenceCode，因此我需要将其与包含demo，offenceType和offenceCode的{​​{1}}进行比较，如果offenceDesc和offenceType 是匹配项，根据我在Google上搜索的内容，我需要从offenceCode中获取offenceDesc，

demo

这是我的stackblitz demo

以前我曾经问过类似prev question的问题，但是尽管尝试了很多次如何解决这个问题，但我还是无法弄清楚，我是编码新手，希望有人可以提出解决问题的建议< / p>

Answer 1

您可以使用地图

const items = [
  {
    offenceType:"7",
    offenceCode:"JLN14",
  }, 
  {
    offenceType:"48",
    offenceCode:"JLN14",
  }
];

const demo = [
  {
    offenceCode: 'JLN14',
    offenceType: '7',
    offenceDesc: 'emergency lane abuse'
  },
  {
    offenceCode: 'JLN14',
    offenceType: '48',
    offenceDesc: 'speeding'
  },
  {
    offenceCode: 'JLN13',
    offenceType: '52',
    offenceDesc: 'parking abuse'
  }
];

const newArray = items.map(item => {
   const lookup = demo.find(i => item.offenceType === i.offenceType);
   return {
     offenceType: lookup.offenceType,
     offenceCode: lookup.offenceCode,
     offenceDesc: lookup.offenceDesc
   }
});

console.log(newArray);

Answer 2

您可以定义一个查找犯罪描述的函数，然后在具有该函数的项目上使用地图

const items = [
  {
    offenceType:"7",
    offenceCode:"JLN14",
  }, 
  {
    offenceType:"48",
    offenceCode:"JLN14",
  }
];

function findOffenseDesc(item) {
    const demo = [
        {
          offenceCode: 'JLN14',
          offenceType: '7',
          offenceDesc: 'emergency lane abuse'
        },
        {
          offenceCode: 'JLN14',
          offenceType: '48',
          offenceDesc: 'speeding'
        },
        {
          offenceCode: 'JLN13',
          offenceType: '52',
          offenceDesc: 'parking abuse'
        }
      ];
      const match = demo.find(offense => offense.offenceCode === item.offenceCode && offense.offenceType === item.offenceType);
      return match && match.offenceDesc;
}

const newArray = items.map(findOffenseDesc);
console.log(newArray); // [ "emergency lane abuse", "speeding" ]

Answer 3

您还可以使用过滤器和地图。假设您只需要犯罪即可

const offenceDescriptions = demo.filter(
    d => items.find(item => item.offenceCode === d.offenceCode
                         && item.offenceType === d.offenceType))
    .map(x => x.offenceDesc)

Answer 4

您可以通过every()方法使用取反逻辑。

相关代码：

...

  newArray = [];

  constructor() { }

  ngOnInit() {
    let  foundOffence: any;

    this.items.forEach(itemsOffence => {
      this.demo.every(demoOffence => {
        let isNoMatch: boolean = demoOffence.offenceCode != itemsOffence.offenceCode || demoOffence.offenceType != itemsOffence.offenceType;
        foundOffence = isNoMatch? undefined: demoOffence;
        return isNoMatch;
      })
      if (foundOffence) {
        console.log(`foundOffenceDesc = ${foundOffence.offenceDesc}`);
        this.newArray.push(foundOffence);
      }
    })
    console.log("newArray = ", this.newArray);
  }

...

您可以看到它在此StackBlitz demo

中工作