016 - js练习题

JS练习题

1. 使用while循环输出 0~100内所有3的倍数

   i = 0
   while (i < 100){
       console.log(i)
       i += 3
   }
   

2. 使用循环计算1*2*3*4*…*10的结果

   total = 1
   for (i=2;i<=10;i+=1){
       total *= i
   }
   console.log(total)
   

3. 统计一个字符串中数字的个数(使用函数进行封装)

   function num_count(str){
   	count = 0
       for (x in str){
           if (str[x] >= '0' && str[x] <= '9'){
               count += 1
           }
       }
       console.log(`字符串${str}数字个数为${count}`)
   }
   num_count('andj84923')
   

4. 计算所有学生平均分

   stu = [
     {name: '大黄', age: 27, score: 60},
   	{name: '小明', age: 18, score: 89},
     {name: '张三', age: 23, score: 92},
     {name: '小花', age: 20, score: 71},
     {name: '小红', age: 30, score: 84}
   ]
   
   total_score = 0
   count = 0
   for(x in stu){
       total_score += stu[x]['score']
       count += 1
   }
   score_average = total_score/count
   console.log(score_average)
   
   //讲解
   sum = 0
   for(x in stu){
       sum += stu[x].score
   }
   console.log(`所有学生平均分为${sum / stu.length}`)
   

5. 求斐波那契数列列中第n个数的值:1，1，2，3，5，8，13，21，34… （这儿的n可以是任意正整数，可以通过输入来确定）

   n = 9
   i = 1
   a = 1
   b = 1
   c = 0
   while (i < n){
       c = a
       a = b
       b = b + c 
       i += 1
   }
   console.log(a)