1 <!DOCTYPE html>
2 <html>
3 <head>
4 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
5 <title></title>
6 <meta charset="utf-8" />
7 <script>
8 //取值范围min-max;
9 //能随机到min和max[min,max]
10 function rnd(min, max) {
11 var tmp = min;
12 if (max < min) { min = max; max = tmp; }//交换值
13 return Math.floor(Math.random() * (max - min + 1) + min); //向下取整
14 }
15 for (i = 0; i < 10; i++) {
16 document.write(rnd(5, 7)+"<br/>");
17 }
18
19 </script>
20 <script>
21 //取值范围min-max;
22 //能随机到min 不能随机到max [min,max)
23 function rnd(min, max) {
24 var tmp = min;
25 if (max < min) { min = max; max = tmp; }//交换值
26 return Math.floor(Math.random() * (max - min) + min); //向下取整
27 }
28 for (i = 0; i < 10; i++) {
29 document.write(rnd(1,5) + "<br/>");
30 }
31 </script>
32 <script>
33 //取值范围min-max;
34 //能随机到max 不能随机到min (min,max]
35 function rnd(min, max) {
36 var tmp = min;
37 if (max < min) { min = max; max = tmp; }//交换值
38 return Math.ceil(Math.random() * (max - min) + min); //向上取整
39 }
40 for (i = 0; i < 10; i++) {
41 document.write(rnd(1, 5) + "<br/>");
42 }
43 </script>
44
45 <script>
46 //取值范围min-max;
47 //不能随机到min和max(min,max)
48 function rnd(min, max) {
49 var tmp = min;
50 var temp;
51 if (max < min) { min = max; max = tmp; }//交换值
52 temp = Math.floor(Math.random() * (max - min + 1) + min); //向下取整
53 if (min == temp) {
54 return min + 1;
55 } else {
56 return temp;
57 }
58 }
59 </script>
60 <!--
61 var a = max/min; a = 7;
62 var xs = (a - 1); xs = 7/1 - 1 = 6;
63 var x=(max-1.0001)/min-1 x ((7-1.0001)/1)-1 = 5.9995; x/xs = 5.9995/6 = 0.99991
64 (7 - 1) * (0.999 *(x/xs))) = 6.9999 向上取整 ==6
65 1 + 6 * (0.1 *(x/xs)) = 1.09991 向上取整 ==2
66 原理是 最小数 + 最小数{(a-1)(随机数)(缩小比例x/xs)}
67 1(1+6)(0.999*0.9999) =
68 当min=1时候; a= max;
69 -->
70 <script>
71 function rnd(min,max){
72 var a = max / min;
73 var xs = (a - 1);
74 var x = (max - 1.0001) / min - 1;
75 return Math.ceil(min * (1 + (a - 1) * (Math.random() *(x/xs))));
76 }
77 for (i = 0; i < 100; i++) {
78 document.write("xxx开区间" + rnd(1,7) + "<br/>");
79 }
80
81 </script>
82 <script>
83 function rnd() {
84
85 return parseInt(Math.random()*5); //取整 随机最大取5; 取值范围 5*(99%到0%)的数 (同上类似)
86 }
87 for (i = 0; i < 10; i++) {
88 document.write(rnd() + "<br />");
89 }
90 </script></head>
91 <body>
92
93 </body>
94 </html>
