质数，只能被自己和1整除的整数。
判断要点1：质数数组默认为[2]， n若能被任意质数数组中的值整除，则不是质数
(function displayPrime() {
let primeArray = [2];
for (let i=3; i< 10000; i++) {
let iIsPrime = true;
for (let prime of primeArray) {
if (i % prime === 0) {
iIsPrime = false;
break;
}
}
if (iIsPrime) {
primeArray.push(i);
}
}
console.info(primeArray);
})();
判断要点2：偶数一定不是质数
(function displayPrime() {
let time1=(new Date()).valueOf();
let primeArray = [2];
for (let i=3; i< 10000; i+=2) {
let iIsPrime = true;
for (let prime of primeArray) {
if (i % prime === 0) {
iIsPrime = false;
break;
}
}
if (iIsPrime) {
primeArray.push(i);
}
}
console.log(‘timeout: ‘+ ((new Date()).valueOf() - time1))
console.info(primeArray);
}());
判断要点3：开平方的结果是整数的整数不是质数
(function displayPrime() {
let time1=(new Date()).valueOf();
let primeArray = [2];
for (let i=3; i< 10000; i+=2) {
let sqrt=Math.sqrt(i), borderNum = i%sqrt;
let iIsPrime = !(borderNum === 0 );
if (!iIsPrime) {
continue;
}
for (let prime of primeArray) {
if (i % prime === 0) {
iIsPrime = false;
break;
}
}
if (iIsPrime) {
primeArray.push(i);
}
}
console.log(‘timeout: ‘+ ((new Date()).valueOf() - time1))
console.info(primeArray);
}());
原文：https://www.cnblogs.com/yiyitong/p/9397631.html