<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>switch输出星期</title> </head> <body> <script type="text/javascript"> var week=new Date().getDay(); console.log(week); //0-6 switch(week){ case 0: document.write("今天是星期日"); break; //退出 case 1: document.write("今天是星期一"); break; case 2: document.write("今天是星期二"); break; case 3: document.write("今天是星期三"); break; case 4: document.write("今天是星期四"); break; case 5: document.write("今天是星期五"); break; default: document.write("今天是星期六"); break; } </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> </head> <body> <script> /*var age=35; if(age<18){ alert("您还没有成年"); }*/ var age=prompt("请输入您的年龄"); console.log(age); if(age<18){ alert("您还没有成年"); }else{ alert("您已成年，请提供您的身份证号"); } </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> </head> <body> <script> var password=prompt("请设置您的密码"); //判断密码的长度，如果不是6位，否则 if(password.length!=6){ alert("请输入6位的数字密码"); }else{ //如果密码是非数字，否则是数字 if(isNaN(password)==true){ alert("密码必须要是数字"); }else{ alert("密码设置正确"); } } </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> </head> <body> <script type="text/javascript"> var str="abc123"; var num=parseInt(str); if(num==NaN){ //NaN和任何内容都不相等，包括它本身 alert(NaN); }else if(num==123){ alert(123); }else if(typeof num=="number"){ alert("num"); }else{ alert("str"); } </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>for</title> </head> <body> <script type="text/javascript"> for(var i=1;i<=100;i++){ document.write(i+'<br/>'); //1 } for(var m=99;m>=1;m-=2){ console.log(m); //99 97 3 1 } alert(m); //-1 </script> </body> </html>