Best way to replace middle element of array (dynamic) in Javascript

Question

I am still pretty new to programing and have been working on challenges. One of them is creating a function that will:

-> Change the middle value in an odd array to a string "Hi" -> Return an even array as it is (no changes)

I have managed to find the middle element in the array with no problem (also setting up the condition for even arrays).

But I am struggling to figure out how to actually replace the element with a string and return the array.

For example [1, 2, 3, 4, 5] -> [1, 2, 'hi", 4, 5]

If anyone can point me in the right direction I would be very grateful. Thank you all for your help

function hiInTheMiddle(arry) {
  if(arry.length % 2 === 0) {
    return arry
  }
  let middle = arry[Math.floor((arry.length - 1) / 2)];
}

You are almost there. Instead of assigning the current element to middle, simply turn it around and assign the new value to the element! (So instead of let middle = stuff you have stuff = 'hi'.) — CherryDT
– CherryDT, Commented Oct 15, 2022 at 17:53

Rohìt Jíndal · Accepted Answer · 2022-10-15 18:30:12Z

2

You can simply achieve this requirement by just finding the index of middle element and then assign the hi string to that index.

Live Demo :

function hiInTheMiddle(arry) {
  if(arry.length % 2 === 0) {
    return arry;
  }
  arry[Math.floor((arry.length - 1) / 2)] = 'hi';
  return arry;
}

const res = hiInTheMiddle([1, 2, 3, 4, 5]);

console.log(res);

edited Oct 15, 2022 at 18:30

answered Oct 15, 2022 at 15:41

Rohìt Jíndal

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1 Comment

Rohìt Jíndal Over a year ago

@CherryDT Thanks for pointing that out. I updated the answer. Hope it will work as per the expectation now.

thisistemporary · Accepted Answer · 2022-10-15 17:49:16Z

1

You can simply change the middle element with arr[middle] = 'Hi'

So the code you need should be something like this:

let evenArr = [1, 2, 3, 4];
let oddArr = [1, 2, 3, 4, 5, 6, 7];
// defined test arrays

function hiInTheMiddle(arr) {
  if (arr.length % 2 === 0) {
    return arr;
  }
  
  arr[arr.length / 2 - 0.5] = 'Hi';
  return arr;
}

console.log(hiInTheMiddle(evenArr), hiInTheMiddle(oddArr));
// test the code

edited Oct 15, 2022 at 17:49

answered Oct 15, 2022 at 11:02

thisistemporary

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Comments

zer00ne · Accepted Answer · 2022-10-15 19:02:45Z

Details are commented in example

const odd = [1, 2, 3, 4, 5];
const even = [1, 2, 3, 4];

/**
 * If array has an odd numbered .length, replace the middle item of array 
 * with a given string.
 * @param {Array} arr  - An array of unknown values
 * @param {String} str - A string to insert into the array. 
 * @return {Array} - If undefined it returns @default as "|". 
 *         If arr .length is even, the array is returned untouched.
 */
const mid = (arr, str = "|") => {
  // If arr is odd...
  if (arr.length % 2 === 1) {
    // replace the middle item with the given string
    arr.splice((arr.length / 2), 1, str);
  }
  return arr;
}

console.log(JSON.stringify(mid(odd)));

console.log(JSON.stringify(mid(even)))

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