javascript variable not changed

Question

I'm trying to do a little program to reverse a string and I'm using this approch:

var reverse = (str) => {
    let returned = [...str];
    for(let i = 0; i < returned.length; i++)
    {
        let symetrical = returned.length - i - 1;
        let temp = returned[i];
        returned[i] = returned[symetrical];
        returned[symetrical] = temp;
    }
    
    return returned.join("");
}

but when i test the function like reverse('123') I got the same input as result?

why the returned variable didn't change?

Tip: JavaScript swapping isn't this hard. [ r[a], r[b] ] = [ r[b], r[a] ] — tadman
– tadman, Commented Oct 28, 2022 at 22:40
The problem is that your loop is swapping each pair of elements twice. This is a common mistake in exercises like this. Change the loop to stop at the halfway point of the array. — Barmar
– Barmar, Commented Oct 28, 2022 at 22:51

symlink · Accepted Answer · 2022-10-28 22:42:47Z

1

You can simplify the function by creating two arrays, the array of the letters of the param str, and the results array which takes the length - 1 - i algorithm you had:

let reverse = (str) => {
    const arr1 = [...str];
    const arr2 = []
    for(let i = 0; i < arr1.length; i++)
    {
        arr2[i] = arr1[arr1.length - 1 - i];
    }
    
    return arr2.join("");
}

console.log(reverse("abcde"));

answered Oct 28, 2022 at 22:42

symlink

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