Prime Number | JavaScript

Prime Number - Let's solve this in a mathematical approach and programmatically using JavaScript.

Any number that is divisible by 1 and itself it's known as a Prime number, for example, 2, 3, 5, 7, 11, 13, and so on.

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[ajalimagno]

At last! I found a simple and easy to understand code for prime number in Javascript :) Thank you so much, my friend :)

[Codehunting]

Hi, your solution is correct. But we can optimise it further by running loop through the square root of the number. Start from 2 and run till the square root of the number. Rest code will be the same.

[raok]

What will happen if we will replace i<n with i<=n
Reply me sir

[girishsoni]

ye console.log() me aapke answer kese aa rahi h, , use ye extention chiye vscode k lie please bataiye

[shubhamshetty]

wht if nis 2, it is prime right but it will enter if statement

[mahendarmanda]

Hi I'm Mahendra Thank you for this video I have one question My question we have in javascript used `${n}` so the same like feature in python could tell me

[niranjanravichandran]

bro i need to clarify something!! why have u written, return `${n} is a prime number ` particularly outside of the for loop?

[Ali-owwr]

This program is not working correctly. Because returning at first divide process. If we enter 9, trying 9 divided by 2 and giving result. It's not even trying for each i values. So here a correct code, you guys can check it.

const isPrime = (n) => {
let count = 0
if(n<=2) {
return `${n} is not prime number`
}

for(let j = 2; j<n; j++) {
if(n%j==0) {
count++
}
}
if(count === 0) {
return `${n} is a prime number.`
}
else {
return `${n} is not prime number`
}
}


console.log(isPrime(9))

[momomeshtv]

why do we need to put a loop if all we need is to check if the n % 2 === 0 or n % 3 === 0??
what's the purpose of using a loop in this?

basically all "not prime" numbers can be divided by 2 or 3,
since you've added a (n < 2) return is not a prime number,

what's the purpose of using a loop?
can't wrap my head around this?

why not just write:

function isPrime(n){
if (n<2)
return 'is not a prime number'

if (n % 2 === 0 || n % 3 === 0) {return 'is not a prime number'}

return 'is a prime number'
}

Thanks

[nareshmote]

9 is not prime number but using this logic 9 is prime number