如果一个属性等于另一个 object 的属性，如何过滤位于对象数组中的 object 的少数属性

Question

I have a object which has some properties for one user, and I have array of objects which is returned from API. My goal is to check which object of Array of objects has the same property as the one single initial object, and then it should return only part of it's properities. I have tried to use.map on Array of objects but it seems not workig.

Below is the code example. I have also prepared codesandbox if You wish.

const user = 
    {
      name: "jan",
      lastName: "kowalski",
      fullName: "jan kowalski",
      car: "audi"
    }
  ;

  const usersAnimal = [
    {
      name: "jan",
      lastName: "kowalski",
      fullName: "jan kowalski",
      animal: "cat",
      animalSize: "small",
      animalName: "Bat"
    },
    {
      name: "john",
      lastName: "smith",
      fullName: "john smith",
      animal: "dog",
      animalSize: "middle",
      animalName: "Jerry"
    },
    {
      name: "Anna",
      lastName: "Nilsson",
      fullName: "Anna Nilsson",
      animal: "cow",
      animalSize: "big",
      animalName: "Dorrie"
    }
  ];

  const filtered = usersAnimal.map((userAnimal)=>userAnimal.fullName === user.fullName && return userAnimal.animalName & userAnimal.animalSize & userAnimal.animal);

thanks

https://codesandbox.io/s/admiring-edison-qxff42?file=/src/App.js

Answer 1

For case like this, it would be far easier if you filter it out first then proceed using map:

 const filtered = usersAnimal
    .filter((animal) => animal.fullName === user.fullName)
    .map(({ animalName, animalSize, animal }) => {
      return {
        animalName,
        animalSize,
        animal
      };
    });

Answer 2

If you want to filter, I recommend you to use filter .

The map method will create a new array, the content of which is the set of results returned by each element of the original array after the callback function is operated

 const user = {name:"jan",lastName:"kowalski",fullName:"jan kowalski",car:"audi"}; const usersAnimal = [{name:"jan",lastName:"kowalski",fullName:"jan kowalski",animal:"cat",animalSize:"small",animalName:"Bat"},{name:"john",lastName:"smith",fullName:"john smith",animal:"dog",animalSize:"middle",animalName:"Jerry"}]; // Get an array of matching objects let filtered = usersAnimal.filter(o => o.fullName === user.fullName); // You get the filtered array, then you can get the required properties filtered.forEach(o => { console.log( 'animal:%s, animalSize:%s, animalName:%s', o?.animal, o?.animalSize, o?.animalName ); }); // Then use map to process each element filtered = filtered.map(o => { const {animal, animalSize, animalName} = o; return {animal, animalSize, animalName}; }); console.log('filtered', filtered);

Answer 3

I am providing a for loop solution as I haven't learnt many array methods in javascript.

For me the simplest option is to use a for loop and an if check to loop through the arrays values to check for included values.

for (let v in usersAnimal) {
    if (usersAnimal[v].fullName === user.fullName) {
        console.log(usersAnimal[v])
    }
}

The code above will log the entire usersAnimal object containing the fullname we are looking for.

{
  name: 'jan',
  lastName: 'kowalski',
  fullName: 'jan kowalski',
  animal: 'cat',
  animalSize: 'small',
  animalName: 'Bat'
}

commented for further understanding

for (let v in usersAnimal) {
//loops though the array
    if (usersAnimal[v].fullName === user.fullName) {
    //when the index value 'v' has a fullname that matches the user fullname value
    // it passes the if check and logs that object value
        return console.log(usersAnimal[v])
    //return true...
    }
  //return null
}

//etc