JavaScript: Create a new string from a given string changing the position of first and last characters

Last update on May 30 2022 10:07:14 (UTC/GMT +8 hours)

JavaScript Basic: Exercise-23 with Solution

Write a JavaScript program to create a new string from a given string changing the position of first and last characters. The string length must be greater than or equal to 1.

Pictorial Presentation:

JavaScript: Create a new string from a given string changing the position of first and last characters

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JavaScript program to create a new string from a given string changing the position of first and last characters.</title>
</head>
<body>
</body>
</html>

JavaScript Code:

function first_last(str1) 
  {
  if (str1.length <= 1)
  {
    return str1;
  }
  mid_char = str1.substring(1, str1.length - 1);
  return (str1.charAt(str1.length - 1)) + mid_char + str1.charAt(0);
}
console.log(first_last('a'));
console.log(first_last('ab'));
console.log(first_last('abc'));

Sample Output:

a
ba
cba

Flowchart:

ES6 Version:

function first_last(str1) 
  {
  if (str1.length <= 1)
  {
    return str1;
  }
  mid_char = str1.substring(1, str1.length - 1);
  return (str1.charAt(str1.length - 1)) + mid_char + str1.charAt(0);
}
console.log(first_last('a'));
console.log(first_last('ab'));
console.log(first_last('abc'));

Live Demo:

See the Pen JavaScript: position of first and last characters.: basic-ex-23 by w3resource (@w3resource) on CodePen.

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Next: Write a JavaScript program to create a new string from a given string with the first character of the given string added at the front and back.

JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());

Ref: https://bit.ly/2BXbp04