javascript 基础知识整理

编写if-else条件语句

if(score>90)
{
    console.log('成绩及格');
}
else
{
    console.log('成绩不及格');
}

 求各个分数段之前的学生个数

var all_math_scores = [143,135,139,148,135,133,143,142,139,142];
var count_A = 0;//存储成绩140分以上的学生的个数
var count_B = 0;//存储成绩在130～140分之间的学生的个数
var count_C = 0;//存储成绩在130分以下的学生的个数
for(var i = 0 ;i <all_math_scores.length;i++)
{
    if(all_math_scores[i]>140)
    {
        count_A = count_A + 1; 
    }
    else if(all_math_scores[i]>130)
    {
     	   count_B = count_B + 1;
    }
    else
    {
        count_C = count_C + 1
    }
}   

 求此学生的三科成绩的最高分，并赋值给变量highest_score

var all_scores = {'杨璐':[131,143,144],
    '王雪':[131,135,144],
    '韩林霖':[127,139,142],
    '沙龙逸':[123,148,136],
    '李鉴学':[126,135,140],  
    '韩雨萌':[129,133,138],
    '刘帅':[116,143,140],
    '康惠雯':[114,142,139],
    '刘钰婷':[115,139,135],
    '林世博':[116,142,129]};
var highest_score ;
var stu_name = '李鉴学';

var arr_scores = all_scores[stu_name];
highest_score = arr_scores[0];
for (var i = 0;i<arr_scores.length;i++)
{
    if(highest_score<arr_scores[i])
    {
        highest_score = arr_scores[i];
    }
}