js 函数的传值问题 

 1 <!DOCTYPE html>
 2 <html>
 3 <head lang="en">
 4     <meta charset="UTF-8">
 5     <title></title>
 6     <script type="text/javascript">
 7 
 8         /**
 9          * 由于函数是对象，所以可以直接把函数通过参数传递进来
10          * @param fun  函数对象
11          * @param arg  参数
12          * @returns {*}
13          */
14         function callFun(fun , arg){
15             //第一个参数就是函数对象
16             return fun(arg);
17         }
18 
19         function say(str){
20             alert("hello:" + str);
21         }
22 
23         function sum(num){
24             return num + 100 ;
25         }
26 
27         //调用了say函数
28         callFun(say , "Leon");  //hello:Leon
29         //调用了sum函数
30         alert(callFun(sum,20));  //120
31 
32         function fn1(arg){
33 
34             /**
35              * 此时返回i的是一个函数对象，
36              */
37             var rel = function(num){
38                 console.info("inner:" + num + " arg: " + arg);
39                 return arg + num ;
40             }
41             console.info("outter arg: " + arg);
42             return rel;
43         }
44 
45         //此时f是一个函数对象,可以完成调用
46         var f = fn1(20);  //控制台输出值：  outter arg: 20
47         console.info(f);   //控制台输出值： function(num)
48         console.info("-------------");
49         alert(f(11));  //控制台输出值：inner:11 arg: 20   运行结果：31
50 
51     </script>
52 
53 </head>
54 <body>
55 
56 </body>
57 </html>

 

 1 <!DOCTYPE html>
 2 <html>
 3 <head lang="en">
 4     <meta charset="UTF-8">
 5     <title></title>
 6 
 7     <script type="text/javascript">
 8 
 9         console.info("10"+1); //111
10         //当进行减法运算时，会自动完成转换
11         console.info("10"-1); //9
12 
13         //根据数字来进行排序的函数
14         function sortByNum(a,b){
15             return a - b ;
16         }
17 
18         var as = [1,2,11,33,12,190];
19         //对应js而言，默认是按照字符串排序
20         as.sort();
21         console.info(as);  // [1, 11, 12, 190, 2, 33]
22 
23         as.sort(sortByNum);
24         console.info(as);  //[1, 2, 11, 12, 33, 190]
25 
26         //根据数字来进行排序的函数
27         function sortByNum2(a,b){
28             return parseInt(a) - parseInt(b) ;
29         }
30         var as2 = [1,2,"11px",33,"12px",190];
31         as2.sort(sortByNum2);
32         console.info(as2);  //[1, 2, "11px", "12px", 33, 190]
33     </script>
34 
35 </head>
36 <body>
37 
38 </body>
39 </html>

 

 

 1 <!DOCTYPE html>
 2 <html>
 3 <head lang="en">
 4     <meta charset="UTF-8">
 5     <title></title>
 6 
 7 
 8 
 9 </head>
10 <body>
11     <div id="person">    </div>
12     <script type="text/javascript">
13 
14         function Person(name,age){
15             this.name = name ;
16             this.age = age ;
17         }
18 
19         var p1 = new Person("Leon",39);
20         var p2 = new Person("John",23);
21         var p3 = new Person("Ada",41);
22         var ps = [p1,p2,p3];
23         ps.sort();
24         console.info(ps);  //[Person { name="Leon",  age=39}, Person { name="John",  age=23}, Person { name="Ada",  age=41}]
25 
26         /**
27          * 使用sortByName sortByAge这两个方法来处理排序，带来的我呢体是需要为每一个属性都设置一个函数
28          * 显然不灵活
29          * 但是如果通过函数的返回值调用就不一样了
30          */
31         function sortByName(obj1 , obj2){
32             if(obj1.name > obj2.name ){
33                 return 1;
34             }else if(obj1.name == obj2.name ){
35                 return 0 ;
36             }else{
37                 return -1 ;
38             }
39         }
40 
41         ps.sort(sortByName);
42         console.info(ps);  //[Person { name="Ada",  age=41}, Person { name="John",  age=23}, Person { name="Leon",  age=39}]
43 
44         function sortByAge(obj1 , obj2){
45             return obj1.age - obj2.age;
46         }
47         ps.sort(sortByAge);
48         console.info(ps);  //[Person { name="John",  age=23}, Person { name="Leon",  age=39}, Person { name="Ada",  age=41}]
49 
50 
51         //改造方法
52         function sortByProperty(propertyName){
53             var sortFun = function(obj1 , obj2){
54                 if(obj1[propertyName] > obj2[propertyName]){
55                     return 1 ;
56                 }else if(obj1[propertyName] == obj2[propertyName]){
57                     return 0 ;
58                 }else{
59                     return -1 ;
60                 }
61             }
62             return sortFun;
63         }
64 
65         ps.sort(sortByProperty("age"));
66         console.info(ps);  //[Person { name="John",  age=23}, Person { name="Leon",  age=39}, Person { name="Ada",  age=41}]
67 
68         ps.sort(sortByProperty("name"));
69         console.info(ps);  //[Person { name="Ada",  age=41}, Person { name="John",  age=23}, Person { name="Leon",  age=39}]
70 
71         function show(){
72             var  p = document.getElementById("person");
73             for(var i = 0 ; i < ps.length ; i ++){
74                 p.innerHTML += ps[i].name + "  ,  " + ps[i].age + "<br/>";
75             }
76         }
77 
78         show();
79     </script>
80 </body>
81 </html>

 

posted @ 2016-03-07 15:18  a757956132  阅读(554)  评论(0)    收藏  举报