1

I have 2 arrays, one of which is filled with elements and the other has empty elements, eg:

let arr1 = ['apples', 'bananas', 'oranges', 'strawberries', 'blueberries', 'pineapple']
let arr2 = [1,,3,,,4]

How do I remove both bananas, strawberries and blueberries and the empty element in arr2, should look something like this:

let arr1 = ['apples', 'oranges', 'pineapple']
let arr2 = [1,3,4]

edit: added more elements to the array for scale.

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5 Answers 5

Reset to default
2

You could map and filter with true because filter omits sparse items.

let array1 = ['apples', 'bananas', 'oranges'],
    array2 = [1, , 3],
    result1 = array2.map((_, i) => array1[i]).filter(_ => true),
    result2 = array2.filter(_ => true);

console.log(result1);
console.log(result2);

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2

You can use Array.prototype.filter():

let arr1 = ['apples', 'bananas', 'oranges', 'strawberries', 'blueberries', 'pineapple'];
let arr2 = [1,,3,,,4];
arr1 = arr1.filter((x, i) => arr2[i] !== undefined);
arr2 = arr2.filter(x => x !== undefined);
console.log(arr1);
console.log(arr2);

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2 Comments

how do i make it so it doesn't filter out 0
@LittleBall Updated to deal with 0s, your example didn't start from 0, I thought if you had more items they would be larger numbers.
1

you can iterate and return only the expected value something like the below snippet

After edit please follow the below snippet

let arr1 = ['apples', 'bananas', 'oranges']
let arr2 = [1, , 3]
var filtered = arr2.filter((item, index) => {
  if (arr2[index] != null) {
    arr1.splice(index, index);
    return true;
  } else {
    return false
  }
});

console.log(filtered);
console.log(arr1);

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3 Comments

how do I scale this for more elements in arr1? I don't wanna hardcode the word 'bananas'
if you dont want to give bananas, What is the strategy how would you like to remove the elements ? I mean on what basis. Please let me know I am not able to understand that part
edited the question for a better understanding
1

You can use filter()

let arr1 = ['apples', 'bananas', 'oranges', 'strawberries', 'blueberries', 'pineapple']
let arr2 = [1,,3,,,4]

let result = arr1.filter((item, index) => {
    return arr2[index] !== undefined;
});

console.log(result); // Outputs: ["apples", "oranges", "pineapple"]

Check this fiddle.

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Comments

0 
const filterOutItems = (array, itemValue = undefined) {
  if (typeof itemValue == undefined) {
    return array.filter((el) => !!el);
  } else {
    return array.filter((el) => el != itemValue);
  }
}

The filter method will return only the items that satisfy the predicate.

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