Course

Introduction

Print Hello World Add Two Numbers Find the Square Root Calculate the Area of a Triangle Swap Two Variables Convert Kilometers to Miles Convert Celsius to Fahrenheit Work With Constants Write to Console

Control Flow

Solve Quadratic Equation Check if a number is Positive, Negative, or Zero Check if a Number is Odd or Even Find the Largest Among Three Numbers Check Prime Number Print All Prime Numbers in an Interval Find the Factorial of a Number Display the Multiplication Table Print the Fibonacci Sequence Check Armstrong Number Find Armstrong Number in an Interval Make a Simple Calculator Find the Sum of Natural Numbers Check if the Numbers Have Same Last Digit Find HCF or GCD Find LCM Find the Factors of a Number Display Fibonacci Sequence Using Recursion

Functions

Generate a Random Number Find Sum of Natural Numbers Using Recursion Guess a Random Number Find Factorial of Number Using Recursion Convert Decimal to Binary Find ASCII Value of Character Set a Default Parameter Value For a Function Check If a Variable is of Function Type Pass Parameter to a setTimeout() Function Perform Function Overloading Pass a Function as Parameter

Arrays and Objects

Shuffle Deck of Cards Create Objects in Different Ways Remove a Property from an Object Check if a Key Exists in an Object Clone a JS Object Loop Through an Object Merge Property of Two Objects Count the Number of Keys/Properties in an Object Add Key/Value Pair to an Object Convert Objects to Strings Replace all Instances of a Character in a String Remove Specific Item From an Array Check if An Array Contains a Specified Value Insert Item in an Array Append an Object to an Array Check if An Object is An Array Empty an Array Add Element to Start of an Array Remove Duplicates From Array Merge Two Arrays and Remove Duplicate Items Sort Array of Objects by Property Values Create Two Dimensional Array Extract Given Property Values from Objects as Array Compare Elements of Two Arrays Get Random Item From an Array Perform Intersection Between Two Arrays Split Array into Smaller Chunks Check If A Variable Is undefined or null Illustrate Different Set Operations

Miscellaneous

Display Date and Time Check Leap Year Format the Date Display Current Date Compare The Value of Two Dates Create Countdown Timer Include a JS file in Another JS file Generate a Random Number Between Two Numbers Get The Current URL Validate An Email Address Implement a Stack Implement a Queue Check if a Number is Float or Integer Get the Dimensions of an Image Convert Date to Number

JavaScript Program to Find Sum of Natural Numbers Using Recursion

To understand this example, you should have the knowledge of the following JavaScript programming topics:

The positive integers 1, 2, 3, … are known as natural numbers.

Example: Sum of Natural Numbers Using Recursion


              
// program to find the sum of natural numbers using recursion

function sum(num) {
    if(num > 0) {
        return num + sum(num - 1);
    }
    else {
        return num;
    }
 }

// take input from the user
const number = parseInt(prompt('Enter a positive integer: '));

const result = sum(number);

// display the result
console.log(`The sum is ${result}`);

Output


              
Enter a positive integer: 5
The sum is 15

In the above program, the user is prompted to enter a number.

Then the sum() function is called by passing the parameter (here 5) that the user entered.

If the number is greater than 0, the function calls itself by decreasing the number by 1.
This process continues until the number is 1. When the number reaches 0, the program stops.
If the user enters a negative number, the negative number is returned and the program stops.

Here,


              
sum(5) returns 5 + sum(4)
sum(4) returns 5 + 4 + sum(3)
sum(3) returns 5 + 4 + 3 + sum(2)
sum(2) returns 5 + 4 + 3 + 2 + sum(1)
sum(1) returns 5 + 4 + 3 + 2 + 1 + sum(0)
sum(0) returns 5 + 4 + 3 + 2 + 1 + 0

Also Read:

JavaScript Program to Find the Sum of Natural Numbers