javascript - Filter array of objects with conditions

Question

I want to filter an array like this:

const myArray = [
    { ageIndex: 4, nameIndex: 1, type: "group" },
    { ageIndex: 4, nameIndex: 0, type: "group" },
    { ageIndex: 5, nameIndex: 0, type: "person" },
    { ageIndex: 5, nameIndex: 1, type: "person" },
    { ageIndex: 5, type: "group" },
];

The new array should filter by unique ageIndex, but only when the type is group. The other objects of type person should stay unchanged. The nameIndex doesn't matter. There are group objects without a nameIndex.

const myNewArray = [
    { ageIndex: 4, nameIndex: 1, type: "group" },
    { ageIndex: 5, nameIndex: 0, type: "person" },
    { ageIndex: 5, nameIndex: 1, type: "person" },
    { ageIndex: 5, type: "group" },
];

How can I filter it like that?

question from:https://stackoverflow.com/questions/65898433/filter-array-of-objects-with-conditions

Answer 1

If you ignore the nameIndex, i hope this could help:

const myArray = [
    { ageIndex: 4, nameIndex: 1, type: "group" },
    { ageIndex: 4, nameIndex: 0, type: "group" },
    { ageIndex: 5, nameIndex: 0, type: "person" },
    { ageIndex: 5, nameIndex: 1, type: "person" },
    { ageIndex: 5, type: "group" },
];

const filterSameGroup = arr => {
  const ageIndexes = [];
  return arr.filter(item => {
    if(item.type === "group") {
      if(ageIndexes.indexOf(item.ageIndex) != -1) {
        return false;
      }
      ageIndexes.push(item.ageIndex);
      return true;
    } 
    return true;
});
}

console.log(filterSameGroup(myArray));