Find all prime factors of a number - JavaScript

We are required to write a JavaScript function that takes in a number and returns an array of all the prime numbers that exactly divide the input number.

For example, if the input number is 18.

Then the output should be −

const output = [2, 3];

Example

Let’s write the code for this function −

const num = 18;
const isPrime = (n) => {
   for(let i = 2; i <= n/2; i++){
      if(n % i === 0){
         return false;
      }
   };
   return true;
};
const findPrimeFactors = num => {
   const res = num % 2 === 0 ? [2] : [];
   let start = 3;
   while(start <= num){
      if(num % start === 0){
         if(isPrime(start)){
            res.push(start);
         };
      };
      start++;
   };
   return res;
};
console.log(findPrimeFactors(18));

Output

The output in the console: −

[2, 3]

AmitDiwan

Updated on: 15-Sep-2020

1K+ Views

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