条件判断语句
简单的if语句
<script type="text/javascript"> var time = new Date().getHours(); var time = 18; if (time < 12) { document.write("Good Mornning") } else if (time > 12 && time < 20) { document.write("Good day you sey") } else { document.write("good evening!!"); } var myDate = new Date(); var a11 = myDate.toISOString(); document.write(a11) </script>
今天的内容大纲
if else 语句
输入一个数，判断它是否能被3、5、9整除，注意考虑同时整除的情况
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> </head> <body> <script> // <!-- 3. 输入一个数，判断它是否能被3、5、9整除，注意考虑同时整除的情况 --> var num = prompt("请用户输入要输入的数字<br>"); if (num % 3 === 0 && num % 5 && num % 9) { document.write("输入的数字能被3 5 9 整除整除<br>") } if (num % 3 == 0 && num % 5 == 0) { document.write("输入的数字能被3 5整除<br>") } if (num % 5 == 0 && num % 9 == 0) { document.write("输入的数字能被 5 9整除<br>") } if (num % 3 == 0 && num % 9 == 0) { document.write("输入的数字能被 3 9整除<br>") } if (num % 3 === 0 || num % 5 == 0 || num % 9 == 0) { document.write("输入的数字能被3 5 9 中的一个数整除<br>") } if (num % 3 === 0) { document.write("输入的数字能被3整除<br>") } if (num % 5 === 0) { document.write("输入的数字能被5整除<br>") } if (num % 7 === 0) { document.write("输入的数字能被9整除<br>") } else{ document.write("输入的数字没有用<br>") } </script> </body> </html>
if语句的多层使用
输六个数，如果其中有二值大于1000，则提示，输入的数值有大于100的
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> </head> <body> <!-- !4.输六个数，如果其中有二值大于1000，则提示，输入的数值有大于100的。 --> <script> var a = prompt("输入的第一个数"); var b = prompt("输入的第二个数"); var c = prompt("输入的第三个数"); var d = prompt("输入的第四个数"); var e = prompt("输入的第五个数"); var f = prompt("输入的第六个数"); if (a > 0 || b > 0 || c > 0 || d > 0 || e > 0 || f > 0) { alert("该数值不为为空") document.write("<h1>" + a + " " + b + " " + c + " " + d + " " + e + " " + a + " " + "</h1>") if (a > 100 && b > 100 || a > 100 && c > 100 || a > 100 && d > 100 || a > 100 && e > 100 || a > 100 && f > 100) { alert("在用户输入中a大于一百" + a + "在b,c,d,e,f中存在一个值大于一百"); document.write("<h1>在用户输入中a大于一百" + a + "在b,c,d,e,f中存在一个值大于一百</h1>") } else if (b > 100 || c > 100 && b > 100 && d > 100 || b > 100 && e > 100 || b > 100 && f > 100) { alert("在用户输入中b大于一百" + b + "在c,d,e,f中存在一个值大于一百"); document.write("在用户输入中b大于一百在c,d,e,f中存在一个值大于一百") } else if (c > 100 && d > 100 || c > 100 && e > 100 || c > 100 && f > 100) { alert("在用户输入中c大于一百" + c + "在d,e,f中存在一个值大于一百"); } else if (d > 100 && e > 100 || e > 100 && f > 100) { alert("在用户输入中d大于一百" + d + "在e,f中存在一个值大于一百") } else if (e > 100 && f > 100) { alert("在用户输入中e大于一百" + e + "在e,f一定大于一百") } else { document.write("用户输入的内容有误") } } </script> </body> </html>
switch语句的使用:Switch Case语句 的使用 用三个案例 来介绍 使用的多种情况
@1获得了星期几
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=<device-width>, initial-scale=1.0"> <title>Document</title> <style> *{ font-size: 30px; } </style> </head> <body> <script> // 获取用户的星期 var day = new Date().getDay(); switch (day) { case 0: document.write("今天是星期天"); break; 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("今天是星期天五"); break; case 6: document.write("今天星期六"); break; default: document.write("今天是job"); } </script> </body> </html>
@2 获得了月份
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> * { font-size: 40px; color: rgb(15, 70, 26); } </style> </head> <body> <script> // 获取用户的月份 var yue = new Date().getMonth(); switch (yue) { case 1: document.write("一月"); break; case 2: document.write("二月"); break; case 3: document.write("三月"); break; case 4: document.write("四月"); break; case 5: document.write("五月"); break; case 6: document.write("六月"); break; case 6: document.write("七月"); break; case 7: document.write("八月"); break; case 8: document.write("九月"); break; case 9: document.write("十月"); break; case 10: document.write("十一月"); break; case 11: document.write("十二月"); break; } </script> </body> </html>
@3 获得每小时的分钟
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> * { font-size: 40px; color: red; } </style> </head> <body> <script> var Minutes = new Date().getMinutes() switch (Minutes) { case 1: document.write(":01"); case 2: document.write(":02"); case 3: document.write(":03"); case 4: document.write(":04"); case 5: document.write(":05"); case 6: document.write(":06"); case 7: document.write(":07"); case 8: document.write(":08"); case 9: document.write(":09"); case 10: document.write(":10"); case 11: document.write(":11"); case 12: document.write(":12"); case 13: document.write(":13"); case 14: document.write(":14"); case 15: document.write(":15"); case 16: document.write(":16"); case 17: document.write(":17"); case 18: document.write(":18"); case 19: document.write(":19"); case 20: document.write(":20"); case 21: document.write(":21"); case 22: document.write(":22"); case 23: document.write(":23"); case 24: document.write(":24"); case 25: document.write(":25"); case 26: document.write(":26"); case 27: document.write(":27"); case 28: document.write(":28"); case 29: document.write(":29"); case 30: document.write(":30"); case 31: document.write(":31"); case 32: document.write(":32"); case 33: document.write(":33"); case 34: document.write(":34"); case 35: document.write(":35"); case 36: document.write(":36"); case 37: document.write(":37"); case 38: document.write(":38"); case 39: document.write(":39"); case 40: document.write(":40"); case 41: document.write(":41"); case 42: document.write(":42"); case 43: document.write(":43"); case 44: document.write(":44"); case 45: document.write(":45"); case 46: document.write(":46"); case 47: document.write(":47"); case 48: document.write(":48"); case 49: document.write(":49"); case 50: document.write(":50"); case 51: document.write(":51"); case 52: document.write(":52"); case 53: document.write(":53"); case 54: document.write(":54"); case 55: document.write(":55"); case 56: document.write(":56"); case 57: document.write(":57"); case 58: document.write(":58"); case 59: document.write(":59"); case 60: document.write(":60"); } </script> </body> </html>
@4获取小时:
// 获取用户的小时 var yue = new Date().getHours(); switch (yue) { case 1: document.write("0:00"); break; case 2: document.write("1:00"); break; case 3: document.write("2:00"); break; case 4: document.write("3:00"); break; case 5: document.write("4:00"); break; case 6: document.write("5:00"); break; case 6: document.write("6:00"); break; case 7: document.write("7:00"); break; case 8: document.write("8:00"); break; case 9: document.write("9:00"); break; case 10: document.write("10:00"); break; case 11: document.write("11:00"); break; default: document.writer("今天是null"); }
循环语句
while语句
//定义的变量 var u = 1; // while(判断的条件) while (u < 12) { // 输出的语句 document.write(u); u = u + 2; }
<script> alert("开始While循环语句学习") var i = 0; while (i < 10) { document.write(i); i++; } document.write("<br><hr>") //定义的变量 var u = 1; // while(判断的条件) while (u < 12) { // 输出的语句 document.write(u); u = u + 2; } </script>
do......while语句
// 声明变量 var i1 = 2; // do{打印的内容和} // while(判断条件) do { document.write(i1); i1++; } while (i1<45);
<script> // 声明变量 var i = 0; // do{打印的内容和} // while(判断条件) do { document.write(i); i++; } while (i < 10); document.write("<hr>") // 声明变量 var i1 = 2; // do{打印的内容和} // while(判断条件) do { document.write(i1); i1++; } while (i1<45); </script>
