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javascriptarraysobjectfilter
blankface
blankface

Reputation: 6347

Filter an array of objects returns empty array

I hae the following array of objects:

arr = [
    {
        name: "john",
        age: 24,
        gender: "male"
    },
    {
        name: "jane",
        age: 27,
        gender: "female"
    },
    {
        name: "joe",
        age: 29,
        gender: "male"
    }
]

I'm trying to filter the name and age property into a new array. I tried this:

const newFields = arr.filter((item) => {
    return (
        item.name && item.age
    );
});

But for some reason newFields returns an empty array.

Upvotes: 0

Views: 1810

Answers (3)

TWS
TWS

Reputation: 56

This can be a one liner too with the arrow function and Parameter Context Matching

const newFields = arr.map(({ name, age }) => ({ name, age }));

Your solution's result can not be empty but the original array, because in this case the return value of your filter function will be always true (every item has the name and age property) which doesn't filter anything from the original arr variable.

Upvotes: 2

J K
J K

Reputation: 944

Instead of .filter() use .map()

const arr = [
  {
    name: "john",
    age: 24,
    gender: "male"
  },
  {
    name: "jane",
    age: 27,
    gender: "female"
  },
  {
    name: "joe",
    age: 29,
    gender: "male"
  }
];

const newFields = arr.map(item => {
  return {
      name: item.name,
      age: item.age
    }
});
console.log(newFields)

Upvotes: 2

gavgrif
gavgrif

Reputation: 15519

If you are creating a new array with a subset of the original - then you can iterate over the array and push the desired elements into its own array.

That said if all you are trying to get is the name and age of the existing array - why do you need to create a separate array? - you can just iterate over the original array and reference only the desired values from each item.

let arr = [
    {
        name: "john",
        age: 24,
        gender: "male"
    },
    {
        name: "jane",
        age: 27,
        gender: "female"
    },
    {
        name: "joe",
        age: 29,
        gender: "male"
    }
]

let newArr = [];

arr.forEach(function(item) {
    newArr.push({name:item.name, age:item.age})
});

console.log(newArr); // gives [{"name": "john","age": 24},{"name": "jane","age": 27},{"name": "joe","age": 29}]

Upvotes: 0

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