js日志组件封装

js日志组件~~
 
 1         function Logger(level) {
             if (!(this instanceof Logger)) {
                 return new Logger();
             }
             var ERROR = 1;
             var INFO = 2;
             var DEBUG = 3;
 
             var logLevel = null;
 
             var levels = {
                 "debug": 3,
                 "info": 2,
                 "error": 1,
                 "none": 0,
             }
 
             if (level === undefined) {
                 logLevel = ERROR;
             } else {
                 logLevel = level;
             }
 
             this.getLevelName = function (level) {
 
                 for (var name in levels) {
                     if (levels[name] == level) {
                         return name;
                     }
                 }
             }
 
             this.setLevel = function (newLevel) {
 
                 logLevel = newLevel;
                 console.log("setting log level to: " + this.getLevelName(newLevel));
             }
 
             var processMessage = function (msg, level) {
                 if (level <= logLevel) {
                     console.log(msg);
                 }
             }
 
             this.error = function (msg) {
                 processMessage(msg, ERROR);
             };
             this.info = function (msg) {
                 processMessage(msg, INFO);
             };
             this.debug = function (msg) {
                 processMessage(msg, DEBUG);
             };
 
             var that = this;
         }
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         var logger = Logger();
         logger.error("haha");