What is the best way to eliminate the first even number from a string?

Question

What is the best way to eliminate the first even number from a string?

My task involves working with a string containing only numbers.

For example:

let inputString = "1234";

The Challenge

I need to create a function that will return the string excluding the first even number, if one exists.

Example Output:

"134"

Sample Code:

let inputString = "1234";

function palindromeRearranging(inputString) {
/// code
}

console.log(palindromeRearranging(inputString));

// The output should be "134"

Attempted Solution

let inputString = "1234"

function palindromeRearranging(inputString) {
  let arr = inputString.split("");
 arr = arr.filter((w)=>{return w % 2 !== 0 })
  return arr.join("")

}

console.log(palindromeRearranging(inputString))

However, this implementation is currently returning a string of all odd numbers.

Please help me understand what I am missing and how I can achieve my desired outcome. Your support is greatly appreciated!

javascript arrays string array-filter

Answer 1

Answer №1

Utilize a regular expression to identify and eliminate any occurrence of characters 02468 in the input string.

function removeEvenNumbers(inputString) {
  return inputString.replace(
    /[02468]/,
    ''
  );
}

console.log(removeEvenNumbers("1234"));

Answer 2

Utilize a regular expression to identify and eliminate any occurrence of characters 02468 in the input string.

function removeEvenNumbers(inputString) {
  return inputString.replace(
    /[02468]/,
    ''
  );
}

console.log(removeEvenNumbers("1234"));

Answer 3

Answer №2

Additionally, one approach is to utilize the .find() method to retrieve the first element that meets a specific condition:

let inputStr = "1234"

function rearrangePalindrome(inputStr) {
  let arr = inputStr.split("");
  const foundNum = arr.find(element => element % 2==0);
  


  return arr.join("").replace(foundNum,'')

}

console.log(rearrangePalindrome(inputStr))

Answer 4

Additionally, one approach is to utilize the .find() method to retrieve the first element that meets a specific condition:

let inputStr = "1234"

function rearrangePalindrome(inputStr) {
  let arr = inputStr.split("");
  const foundNum = arr.find(element => element % 2==0);
  


  return arr.join("").replace(foundNum,'')

}

console.log(rearrangePalindrome(inputStr))

Answer 5

Answer №3

In this code snippet, you are eliminating all even numbers from a string except for the first one.

The solution provided by @CertainPerformance seems to be working well.

If you wish to refine your function further, you may consider using my snippet below.

let inputString = "13"

function removeEvenNumbers(inputString) {
  let arr = inputString.split("");
  let evenNumbers = arr.filter((num)=>{return num % 2 === 0 });
  if (evenNumbers.length < 1){
    return inputString;
  }
  arr.splice(arr.indexOf(evenNumbers[0]), 1);
  return arr.join("");
}

console.log(removeEvenNumbers(inputString))

Answer 6

In this code snippet, you are eliminating all even numbers from a string except for the first one.

The solution provided by @CertainPerformance seems to be working well.

If you wish to refine your function further, you may consider using my snippet below.

let inputString = "13"

function removeEvenNumbers(inputString) {
  let arr = inputString.split("");
  let evenNumbers = arr.filter((num)=>{return num % 2 === 0 });
  if (evenNumbers.length < 1){
    return inputString;
  }
  arr.splice(arr.indexOf(evenNumbers[0]), 1);
  return arr.join("");
}

console.log(removeEvenNumbers(inputString))

Answer 7

Answer №4

Your function is very close to the correct solution. At the moment, you are filtering out all even numbers because you forgot to check if it's the first one.

Take into account the following:

let inputString = "1234";

function palindromeRearranging(inputString) {
  let arr = inputString.split("");
  let firstWasFound = false;
  arr = arr.filter((w)=> {
    if(firstWasFound) {
      return true;
    }
    const isOdd = w % 2 !== 0;
    if(!isOdd){
      firstWasFound = true;
      return false;
    }
    return isOdd;
  })
  return arr.join("")
}


console.log(palindromeRearranging(inputString));

The variable firstWasFound is utilized to ensure removal only happens once.

Answer 8

Your function is very close to the correct solution. At the moment, you are filtering out all even numbers because you forgot to check if it's the first one.

Take into account the following:

let inputString = "1234";

function palindromeRearranging(inputString) {
  let arr = inputString.split("");
  let firstWasFound = false;
  arr = arr.filter((w)=> {
    if(firstWasFound) {
      return true;
    }
    const isOdd = w % 2 !== 0;
    if(!isOdd){
      firstWasFound = true;
      return false;
    }
    return isOdd;
  })
  return arr.join("")
}


console.log(palindromeRearranging(inputString));

The variable firstWasFound is utilized to ensure removal only happens once.

Answer 9

Answer №5

You can achieve this using the methods Array#findIndex and Array#slice.

The Array#findIndex function will find the first matching occurrence and then stop the loop execution.
After finding the index, you can split the array by using the Array#slice method based on the matched index.
Using parseInt will return a number instead of a string.

let inputString = "1131"

function palindromeRearranging(inputString) {
  let arr = inputString.split("");
  let ind = arr.findIndex(a => a % 2 === 0)
  let res = ind === -1 ? arr :[...arr.slice(0, ind), ...arr.slice(ind + 1, arr.length)]
  return parseInt(res.join(''))
}

console.log(palindromeRearranging(inputString))

Answer 10

You can achieve this using the methods Array#findIndex and Array#slice.

The Array#findIndex function will find the first matching occurrence and then stop the loop execution.
After finding the index, you can split the array by using the Array#slice method based on the matched index.
Using parseInt will return a number instead of a string.

let inputString = "1131"

function palindromeRearranging(inputString) {
  let arr = inputString.split("");
  let ind = arr.findIndex(a => a % 2 === 0)
  let res = ind === -1 ? arr :[...arr.slice(0, ind), ...arr.slice(ind + 1, arr.length)]
  return parseInt(res.join(''))
}

console.log(palindromeRearranging(inputString))

What is the best way to eliminate the first even number from a string?

The Challenge

Attempted Solution

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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