js日志组件~~

 1         function Logger(level) {
 2             if (!(this instanceof Logger)) {
 3                 return new Logger();
 4             }
 5             var ERROR = 1;
 6             var INFO = 2;
 7             var DEBUG = 3;
 8 
 9             var logLevel = null;
10 
11             var levels = {
12                 "debug": 3,
13                 "info": 2,
14                 "error": 1,
15                 "none": 0,
16             }
17 
18             if (level === undefined) {
19                 logLevel = ERROR;
20             } else {
21                 logLevel = level;
22             }
23 
24             this.getLevelName = function (level) {
25 
26                 for (var name in levels) {
27                     if (levels[name] == level) {
28                         return name;
29                     }
30                 }
31             }
32 
33             this.setLevel = function (newLevel) {
34 
35                 logLevel = newLevel;
36                 console.log("setting log level to: " + this.getLevelName(newLevel));
37             }
38 
39             var processMessage = function (msg, level) {
40                 if (level <= logLevel) {
41                     console.log(msg);
42                 }
43             }
44 
45             this.error = function (msg) {
46                 processMessage(msg, ERROR);
47             };
48             this.info = function (msg) {
49                 processMessage(msg, INFO);
50             };
51             this.debug = function (msg) {
52                 processMessage(msg, DEBUG);
53             };
54 
55             var that = this;
56         }
-----------------------------------------------------------
58         var logger = Logger();
59         logger.error("haha");