"use strict"; const isPrimeNumber = (number) => { let isPrime = (number < 2) ? false: true; // set default return value for (let i = 2; i < number; i++) { if ( number % i === 0 ) { isPrime = false; break; } } return isPrime; }; $(document).ready( () => { $("#calculate").click( () => { const number = parseInt( $("#number").val() ); if ( isNaN(number) ) { $("#message").text( "Please enter a number." ); } else { $("#message").text(""); for (let i = 1; i <= number; i++) { const isPrime = isPrimeNumber(i); if (isPrime) { $("#message").text( $("#message").text() + i + " " ); } else { continue; } } // const isPrime = isPrimeNumber( number ); // if ( isPrime === true ) { // $("#message").text( number + " is a prime number." ); // } else { // $("#message").text( number + " is NOT a prime number." ); // } } $("#number").focus(); $("#number").select(); }); $("#number").focus(); });