JavaScript prototype to find two primes whose sum is the given number

This program finds two prime numbers whose sum is the number provided by the user.

Took 8 minutes and 3 seconds to code JavaScript prototype to find two primes whose sum is the given number. Here is the code snippet.

Code (Run Code):

function checkPrime(num) {

if (num == 1) {

return false;

} else if (num == 2) {

return true;

}

for (var x = 2; x < num; x++) {

if (num % x == 0) {

return false;

}

}

return true;

}

function primeSum(num) {

arr = [];

for (var i = 2; i < num; i++) {

if (checkPrime(i)) {

arr.push(i);

}

}

for (var i = 0; i < arr.length; i++) {

for (var j = 0; j < arr.length; j++) {

if (arr[i] + arr[j] == num) {

return arr[i] + ' + ' + arr[j] + ' = ' + num;

}

}

}

}

function main(){

document.getElementById("result").innerHTML =

primeSum(document.getElementById("num").value);

}