JavaScript 斐波那契數(shù)列 倒序輸出 輸出100以內(nèi)的質(zhì)數(shù)代碼實(shí)例

//求斐波那契數(shù)列第n位
var n = parseInt(window.prompt('輸入你要求的斐波那契數(shù)列的位數(shù)'));
var first = 1,
  second = 1,
  third;
if (n > 2) {
  for (var i = 0; i < n - 2; i++) {
    third = first + second;
    first = second;
    second = third;
    document.writeln('斐波那契數(shù)列的第' + (i + 3) + '位是：' + third)
  }
} else {
  document.writeln(1);
}

 //倒序輸出
 var n = window.prompt("請(qǐng)輸入三位數(shù)的整數(shù)");
 for (var i = n.length; i >= 0; i--) {
   document.writeln(n.charAt(i));
 }
 document.writeln(a);

//判斷是否質(zhì)數(shù)
var count = 0; //計(jì)數(shù)器
for (var i = 1; i < 100; i++) {
  //看每個(gè)i是否質(zhì)數(shù)
  for (var j = 1; j <= i; j++) {
    if (i % j == 0) {
      //統(tǒng)計(jì)被整除的次數(shù)
      count++;
    }
  }
  //如果被整除的次數(shù)等于2次，則輸出這個(gè)數(shù)
  if (count == 2) {
    document.writeln(i + " ");
  }
  //計(jì)數(shù)器清零
  count=0;
}