TypeScript generic swap function example

TypeScript Advance Types: Exercise-10 with Solution

Write a TypeScript generic function that accepts two arguments: an array of any type and two indices. The function should swap the elements at the specified indices and return the modified array.

Sample Solution:

TypeScript Code:

// Generic function 'swap' that accepts an array and two indices
function swap(arr: T[], index1: number, index2: number): T[] {
  // Check if the indices are within the valid range
  if (index1 < 0 || index1 >= arr.length || index2 < 0 || index2 >= arr.length) {
    throw new Error("Invalid indices");

  // Perform the swap using a temporary variable
  const temp: T = arr[index1];
  arr[index1] = arr[index2];
  arr[index2] = temp;

  return arr;
// Test the 'swap' function with an array of numbers
const nums: numbers[] = [21, 45, 76, 87, 14];

console.log("Original Array:", nums);
swap(nums, 1, 3); // Swap elements at indices 1 and 3
console.log("Modified Array:", nums);


In the exercise above -

  • First, we define a generic function "swap()" that accepts three parameters: an array arr of type T[] (an array of any type), and two indices 'index1' and 'index2'.
  • Inside the function, we first check if the indices are within the valid range (between 0 and arr.length - 1). If the indices are invalid, we throw an error.
  • We then perform the swap operation using a temporary variable 'temp'.
  • Finally, we return the modified array 'arr' after the swap operation.


"Original Array:"
[21, 45, 76, 87, 14]
"Modified Array:"
[21, 87, 76, 45, 14]

TypeScript Editor:

See the Pen TypeScript by w3resource (@w3resource) on CodePen.

Previous: TypeScript generic function example.
Next: TypeScript Mapped Type: Making properties optional.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.

Follow us on Facebook and Twitter for latest update.