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

JavaScript Basic: Exercise-23 with Solution

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

This JavaScript program creates a new string from a given string by swapping the positions of the first and last characters. It ensures that the length of the string is greater than or equal to 1 to perform the swap operation safely. By using string manipulation methods like charAt() and concatenation, it constructs the new string with the first and last characters swapped.

Visual Presentation:

Sample Solution:

JavaScript Code:

// Define a function named first_last that takes a parameter str1
function first_last(str1) {
  // Check if the length of str1 is less than or equal to 1
  if (str1.length <= 1) {
    // If true, return str1 as is
    return str1;
  }
  // Extract the substring from the second character to the second-to-last character of str1
  mid_char = str1.substring(1, str1.length - 1);
  // Return the last character of str1 followed by mid_char and then the first character of str1
  return (str1.charAt(str1.length - 1)) + mid_char + str1.charAt(0);
}

// Log the result of calling the first_last function with the argument 'a' to the console
console.log(first_last('a'));

// Log the result of calling the first_last function with the argument 'ab' to the console
console.log(first_last('ab'));

// Log the result of calling the first_last function with the argument 'abc' to the console
console.log(first_last('abc')); 

Output:

a
ba
cba

Live Demo:

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

Flowchart:

ES6 Version:

 // Using ES6 arrow function syntax to define the first_last function
const first_last = (str1) => {
  // Check if the length of str1 is less than or equal to 1
  if (str1.length <= 1) {
    // If true, return str1 as is
    return str1;
  }
  // Extract the substring from the second character to the second-to-last character of str1
  const mid_char = str1.substring(1, str1.length - 1);
  // Return the last character of str1 followed by mid_char and then the first character of str1
  return (str1.charAt(str1.length - 1)) + mid_char + str1.charAt(0);
};

// Log the result of calling the first_last function with the argument 'a' to the console
console.log(first_last('a'));

// Log the result of calling the first_last function with the argument 'ab' to the console
console.log(first_last('ab'));

// Log the result of calling the first_last function with the argument 'abc' to the console
console.log(first_last('abc'));

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