function isPrime(n) {
if (n <= 3) { return n > 1 }
if (n % 2 == 0 || n % 3 == 0) { return false }
for (var i = 5 i * i <= n i += 6) {
if (n % i == 0 || n % (i + 2) == 0) {
return false
}
}
return true
}
// 测试
console.log(isPrime(2)) // true
console.log(isPrime(3)) // true
console.log(isPrime(4)) // false
console.log(isPrime(5)) // true
运行结果：
参考下面代码function isprime(x)
{
for(var i = 2i <sqrt(x)i++)
if(isdiv(x, i) == 0) return false
return true
}
<html><head>
</head>
<body>
<script type="text/javascript">
var sum = 0//定义一个变量装和
var zhisu = ""
for(var i=1 i<=100i++){ //从1到100加
var iszs = true
for(var j=2j<ij++){
if(i%j==0){
iszs = false
break
}
}
if(iszs){
zhisu += i + ","
sum+=i //等于sum = sum + i
}
}
alert("质数有:"+zhisu)
alert(sum)
</script>
</body>
</html>
