JS入门第一节

                点击触发页面弹窗                    alert('努力，奋斗');    

alert('努力，奋斗')

alert('你好 JS~')document.write('JavaScript 我来了！')console.log('它~会魔法吧~')

        let num = 20;        let uname = '张三';        console.log(`num = ${num}, uname = ${uname}`);

        let name;        name = prompt('请输入姓名:');        document.write('您的姓名为: ' + name);

        let num1 = 10;        let num2 = 20;        let temp = num1;        num1 = num2;        num2 = temp;        document.write(`num1 = ${num1}, num2 = ${num2}`);

        let uname, age, gender;        uname = prompt('请输入您的姓名：');        age = prompt('请输入您的年龄：');        gender = prompt('请输入您的性别：');        document.write(`uname = ${uname}, age = ${age}, gender = ${gender}`);

        let week = [            '星期一',            '星期二',            '星期三',            '星期四',            '星期五',            '星期六',            '星期日',        ]        document.write(week[6]);

        const pi = 3.14;        let area;        let r = prompt('请输入半径');        are = pi * r * r;        document.write('圆的面积为:'+area);

        let uname, age;        uname = prompt('请您输入姓名');        age = prompt('请您输入年龄');        document.write(`大家好，我叫${uname},今年${age}岁了`);

        let num1, num2;        num1 = prompt('请输入第一个数');        num2 = prompt('请输入第二个数');        document.write(`sum = ${Number(num1) + parseInt(num2)}`);

        let price, num, address;        price = prompt('请输入商品价格:');        num = prompt('请输入商品数量:');        address = prompt('请输入收货地址:');        document.write(`price = ${price}, num = ${num}, address = ${address}`);

            h2 {          text-align: center;        }            table {          /* 合并相邻边框 */          border-collapse: collapse;          height: 80px;          margin: 0 auto;          text-align: center;        }            th {          padding: 5px 30px;        }            table,        th,        td {          border: 1px solid #000;        }                  
订单确认
                 let price, num, address;          price = prompt('请输入商品价格:');        num = prompt('请输入商品数量:');        address = prompt('请输入收货地址:');        let sum = price * num;        document.write(`                        
                
                    
商品名称
                    
商品价格
                    
商品数量
                    
总价
                    
收货地址
                
                
                                       
小米手机青春PLUS
                    
${price}元
                    
${num}
                    
${sum}元
                    
${address}
                
            
        `);      

📖 补充

        /*        string、string1、NAN、pink1        如果一个只要有一个字符串的+运算，作用就是拼接 [如果+位于字符串前，作用是将字符串转为数字]        其他运算符 - * / % 会将式子转为数学运算        typeof 运算符的优先级更高    */    console.log(typeof "1")    console.log(typeof '1' + 1)    console.log('1' - 1)    console.log('pink' + 1)

        let number = prompt('请输入一个数:');        if(number % 4 === 0 && number % 100 !== 0){            alert(true);        }else{            alert(false);        }

        let a = 3 > 5 && 2 < 7 && 3 == 4        console.log(a);        let b = 3  1 || 3 != 2        console.log(b);        let c = 2 === "2"        console.log(c);        let d = !c || b && a        console.log(d);        // false、true、false、true

        let score = prompt('请输入您的高考成绩:')        if(score > 700){            alert('恭喜考入黑马程序员')        }

        let uname = prompt('请输入用户名:');        let password = prompt('请输入密码:');        if(uname === 'pink' && password === '123456'){            alert('登录成功');        }else{            alert('登录失败');        }

        let year = prompt('请输入年份:');        if((year % 4 === 0 && year % 100 !== 0) || (year % 400 === 0)){            alert('闰年');        }else{            alert('平年');        }

        let grade = prompt('请输入您的成绩:');        if(grade >= 90){            alert('优秀');        }else if(grade >= 70){            alert('良好');        }else if(grade >= 60){            alert('及格');        }else{            alert('不及格');        }

        let num1 = prompt('请输入第一个数');        let num2 = prompt('请输入第二个数');        console.log(num1 > num2 ? num1 : num2);

        let num1 = parseFloat(prompt('请输入第一个数'));        let num2 = parseFloat(prompt('请输入第二个数'));        let option = prompt('请输入操作符')        let result;        switch(option){            case '+':                result = num1 + num2;                break;            case '-':                result = num1 - num2;                break;            case '*':                result = num1 * num2;                break;            case '/':                result = num1 / num2;                break;            default:                alert('请在 + - * / 中选择操作符:');                break;        }        alert('运算的结果为: ' + result);

        let i = 0;        while(i < 10){            document.write('月薪过万' + `
`);            i++;                   }

        while(prompt('你爱我吗') !== '爱'){}

            let money = 100;        while(true){            let op = prompt(`            请输入您选择的功能：                1.存钱                2.取钱                3.查看余额                4.退出系统            `);            if(op === '4'){                break;            }            switch(op){                case '1':                    m = Number(prompt('请输入您要存入的额度:'));                    money += m;                    break;                case '2':                     m = Number(prompt('请输入您要取出的额度:'));                    money -= m;                    break;                case '3':                    alert('您当前的余额为:' + money);                    break;                default:                    alert('请重新选择操作');                    break;            }        }