1.數(shù)字轉換為字母

var ch = String.fromCodePoint( parseInt(t) + 64)  //大寫
ch = String.fromCodePoint( parseInt(t) + 96 )      //小寫

2.== & ===
https://www.zhihu.com/question/20348948
2.數(shù)學運算

parseInt(4/3)            //取整
Math.ceil(4/3)           //向上取整
Math.round(4/3)       //四舍五入
Math.floor(4/3)         //向下取整

Math函數(shù)的一些其他方法

abs(x)            //絕對值
exp(x)            //e的指數(shù)
max(x,y)
min(x,y)
pow(x,y)        //x的y次冪
random()        //0-1之間的隨機數(shù)
round(x)        //四舍五入為一個最接近的整數(shù)
valueOf()       //返回Math對象的原始值

3.輸出

• 控制臺輸出console.log()
• 對話框輸入：a = prompt（1+2=?）?

對話框輸入的結果即為a的值

4.增強for循環(huán)

• for in（i為數(shù)組下標）

var stu_scores = {'楊璐':131,
    '王雪':131,
    '韓林霖':127,
    '沙龍逸':123,
    '李鑒學':126,
    '韓雨萌':129,
    '劉帥':116,
    '康惠雯':114,
    '劉鈺婷':115};
var stu_names = ['楊璐',
    '王雪',
    '韓林霖',
    '沙龍逸',
    '李鑒學',
    '韓雨萌',
    '劉帥',
    '康惠雯',
    '劉鈺婷'];
var scores = [];
var highest_score = 0;
//使用for循環(huán)取出成績數(shù)組，打印所有成績，找到做高分
for(var i in stu_names){
    var score = stu_scores[stu_names[i]]
    scores.push(score)
    if(score > highest_score)
        highest_score = score
}
//獲取所有學生的分數(shù)(只包含學生分數(shù)不包含學生姓名)存到scores中

var highest_score = scores[0];
//使用for循環(huán)找出學生成績的最高分

console.log('學生成績的最高分:'+highest_score);

• forEach

stu_names.forEach(name =>{
 var score = stu_scores[name]
    scores.push(score)
    if(score > highest_score)
        highest_score = score
})

• forEach

stu_names.forEach(function(name){
 var score = stu_scores[name]
    scores.push(score)
    if(score > highest_score)
        highest_score = score
})