How to find the factorial sum from 1 to 10 in JavaScript

Factorial refers to the product of all integers from 1 to a certain positive integer n. The common symbol is n!, such as 3! = 3 × 2 × 1 = 6.

In JavaScript, you can use loops and recursion to solve factorial sums from 1 to 10.

1. Use loops to solve

A loop is a method of repeatedly executing the same block of code, which can be implemented using a for or while loop statement. Here, we use a for loop to calculate the factorial sum from 1 to 10.

Code:

let sum = 0;
for (let i = 1; i <= 10; i++) {
  let fact = 1;
  for (let j = i; j >= 1; j--) {
    fact *= j;
  }
  sum += fact;
}
console.log(sum); // 输出 4037913

Explanation:

First, we define a sum variable to store the factorial sum.

Next, we use a for loop to iterate each number i from 1 to 10, and in each loop, define a variable fact to calculate the factorial of i.

The second for loop inside iterates each number j from i to 1 and calculates the product fact = fact * j.

Finally, add fact to sum in order to calculate the factorial sum.

2. Solve using recursion

Recursion is a method of solving a problem by itself breaking it into smaller sub-problems. Here we use recursion to calculate the factorial sum from 1 to 10.

Code:

function factorial(num) {
  if (num === 0) return 1;
  return num * factorial(num - 1);
}

let sum = 0;
for (let i = 1; i <= 10; i++) {
  sum += factorial(i);
}
console.log(sum); // 输出 4037913

Explanation:

First, we define a factorial function that accepts an integer as input and recursively calculates the factorial of the integer. If the input is 0, the function returns 1.

Next, we use a for loop to iterate over each number i from 1 to 10 and call the factorial function to calculate the factorial of i.

Finally, add the calculated factorial to sum to calculate the factorial sum.

Whether using loops or recursion, factorial sums from 1 to 10 can be calculated efficiently. But for larger numbers, it's better to use recursion because nesting of loops may lead to increased code complexity, while recursion makes it easier to handle larger numbers.

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