JavaScript: Get the integers in a range

JavaScript Function: Exercise-3 with Solution

Range of Integers Using Recursion

Write a JavaScript program to get integers in the range (x, y) using recursion.

Example : range(2, 9)
Expected Output : [3, 4, 5, 6, 7, 8]

Visual Presentation:

Sample Solution-1:

JavaScript Code:

// Function to generate a range of numbers between start_num and end_num (exclusive).
var range = function(start_num, end_num) 
{
  // Base case: if the difference between end_num and start_num is 2,
  // return an array containing the number between them.
  if (end_num - start_num === 2) 
  {
    return [start_num + 1];
  } 
  else 
  {
    // Recursive case: generate the range between start_num and end_num - 1,
    // then push the current end_num - 1 to the array.
    var list = range(start_num, end_num - 1);
    list.push(end_num - 1);
    return list;
  }
};

// Example usage: Generate and print the range of numbers between 2 and 9 (exclusive).
console.log(range(2, 9));

Output:

[3,4,5,6,7,8]

Flowchart:

Live Demo:

See the Pen javascript-recursion-function-exercise-3 by w3resource (@w3resource) on CodePen.

Sample Solution-2:

JavaScript Code:

// Function to get integers in the range (x, y) using recursion.
function getRangeIntegers(x, y, result = []) {
  // Base case: if x is equal to or greater than y, return the result.
  if (x >= y - 1) {
    return result;
  } else {
    // Recursive case: increment x and push it to the result array.
    result.push(x + 1);
    return getRangeIntegers(x + 1, y, result);
  }
}

// Example usage: Get and print integers in the range (2, 9).
console.log(getRangeIntegers(2, 9));

Output:

[3,4,5,6,7,8]

Flowchart:

For more Practice: Solve these Related Problems:

• Write a JavaScript function that returns an array of integers between two numbers recursively, excluding the endpoints.
• Write a JavaScript function that generates a range of integers recursively, supporting both ascending and descending orders.
• Write a JavaScript function that recursively creates a range of integers and throws an error if the start is greater than the end.
• Write a JavaScript function that uses recursion to generate a range of integers and returns the result in reverse order.

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