Passing a variable to filter callback function

Question

When passing a callback to filter. value, index and Array object is passed to the callback parameters, so how is it possible for me to create a reusable filter callback where i can pass any animal type and filter accordingly.

I did look at How do I pass an extra parameter to the callback function in Javascript .filter() method? but could not get it to work as intended

let animals = [
  { name: "fiddo", type: "dog" },
  { name: "garfield", type: "cat" },
  { name: "diddi", type: "bird" },
  { name: "bob", type: "cat" },
];

This is what i want to do, I know it is not possible, but how could i achive something "similar"?

function filterAnyAnimal(animal, index, arr, typeVariable) {
  if (animal.type === typeVariable) {
    return true;
  }
  return false;
}

console.log(animals.filter(filterAnyAnimal));

do i really have to do like this? or is there a way to pass a variable?


function isDog(animal) {
  if (animal.type === "dog") {
    return true;
  }
  return false;
}

You can do what the [accepted answer](https://stackoverflow.com/a/7759286/218196) of the question you linked to suggests: Make `filterAnyAnimal` accept `typeVariable` as parameter and let it *return* a filter function. Then use it as `animals.filter(filterAnyAnimal('dog'))`. — Felix Kling, Sep 21 '22 at 20:34

score 1 · Accepted Answer · answered Sep 21 '22 at 20:44

As felix-kling comment said and his already answer, you could do:

let animals = [
  { name: "fiddo", type: "dog" },
  { name: "garfield", type: "cat" },
  { name: "diddi", type: "bird" },
  { name: "bob", type: "cat" },
];
function filterAnyAnimal(typeVariable, animalType) {
   if (animalType === typeVariable) {
    return true;
  }
  return false;
}
let wordToFilter = 'cat';
console.log(animals.filter(function(element){
    return filterAnyAnimal(element.type, wordToFilter);
}));

score 1 · Answer 2 · answered Sep 21 '22 at 20:50

let animals = [
  { name: "fiddo", type: "dog" },
  { name: "garfield", type: "cat" },
  { name: "diddi", type: "bird" },
  { name: "bob", type: "cat" },
];

const result = animals.map(animal=>animal.type==="dog"?true:false);

console.log(result);

Map function can give you the desired result

Passing a variable to filter callback function

2 Answers2