To Make alternating array

September 3, 2023

I am learning the basics and I just cannot hack this one:
This function will be called with an array and should return a new array containing only the alternate elements starting from index 0. If the array is empty or contains only 1 item, return the original array.

makeAlternatingArray(['hey', 'hi']);
// should return ['hey']

makeAlternatingArray(['a', 'b', 'c', 'd', 'e']);
// should return ['a', 'c', 'e']

What I got so far is:

function makeAlternatingArray(array) {
    if (array.length<=1){
        return array
    }
    for (let i=0; i<array.length; i=+2){
        return array[i]
    }
    
}

Top part is correct but by for let statement is wrong. I am getting these errors:
When passed an array of multiple elements, function will return an array of alternating items
✕ AssertionError: expected ‘a’ to deeply equal [ ‘a’, ‘c’, ‘e’ ]

When passed an array of multiple elements, function will return an array of alternating items
✕ AssertionError: expected 100 to deeply equal [ 100, 99, -5 ]

Can someone help please?

function makeAlternatingArray(array) {
    if (array.length<=1){
        return array
    }
    for (let i=0; i<array.length; i=+2){
        return array[i]
    }
    
}

>Solution :

function makeAlternatingArray(array) {
    if (array.length<=1){
        return array
    }
    return array.filter((el, i) => i % 2 === 0);
}

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

function makeAlternatingArray(array) {
    if (array.length<=1){
        return array
    }
    let newArray = [];
    for (let i=0; i<array.length; i=+2){
        newArray.push(array[i]);
    }
    return newArray;
}