简易 Javascript 调试包 Debug包_javascript技巧-tutorial js-php.cn

来看一个简易的 Javascript 调试包：jscript.debug.js，包含两个函数，第一个用来遍历对象的各个属性；第二个是一个通用的 Debug 函数（其实说‘对象'比较‘精确些'，呵呵），用来规定各种错误级别及其各种提示、错误信息的格式化显示，还是《Javascript 实战》上面的经典例子，先看源码：

复制代码代码如下:

/** 
* jscript.debug package 
* This package contains utility functions for helping debug JavaScript. 
* 
*/ 
/*命名空间*/ 
if (typeof jscript == 'undefined') { 
jscript = function() { } 
} 
jscript.debug = function() { } 

/** 
* This simple function is one of the handiest: pass it an object, and it 
* will pop an alert() listing all the properties of the object and their 
* values.（这个函数用来遍历对象的属性及其相应的值，并显示出来） 
* 
* @param inObj The object to display properties of. 
*/ 
jscript.debug.enumProps = function(inObj) { 

var props = ""; 
var i; 
for (i in inObj) { 
props += i + " = " + inObj[i] + "\n"; 
} 
alert(props); 

} // End enumProps(). 

/** 
* This is a very simple logger that sends all log messages to a specified 
* DIV.（这是一个简单的 debug 日志记录系统） 
*/ 
jscript.debug.DivLogger = function() { 

/** 
* The following are faux constants that define the various levels a log 
* instance can be set to output.（下面的常量用来定义错误级别） 
*/ 
this.LEVEL_TRACE = 1; 
this.LEVEL_DEBUG = 2; 
this.LEVEL_INFO = 3; 
this.LEVEL_WARN = 4; 
this.LEVEL_ERROR = 5; 
this.LEVEL_FATAL = 6; 

/** 
* These are the font colors for each logging level.（定义各种错误的显示颜色） 
*/ 
this.LEVEL_TRACE_COLOR = "a0a000"; 
this.LEVEL_DEBUG_COLOR = "64c864"; 
this.LEVEL_INFO_COLOR = "000000"; 
this.LEVEL_WARN_COLOR = "0000ff"; 
this.LEVEL_ERROR_COLOR = "ff8c00"; 
this.LEVEL_FATAL_COLOR = "ff0000"; 

/** 
* logLevel determines the minimum message level the instance will show.（需要显示的最小错误级别，默认为 3） 
*/ 
this.logLevel = 3; 

/** 
* targetDIV is the DIV object to output to. 
*/ 
this.targetDiv = null; 

/** 
* This function is used to set the minimum level a log instance will show. 
*（在这里定义需要显示的最小错误级别） 
* @param inLevel One of the level constants. Any message at this level 
* or a higher level will be displayed, others will not. 
*/ 
this.setLevel = function(inLevel) { 

this.logLevel = inLevel; 

} // End setLevel(). 

/** 
* This function is used to set the target DIV that all messages are 
* written to. Note that when you call this, the DIV's existing contents 
* are cleared out.（设置信息显示的 DIV，调用此函数的时候，原有的信息将被清除） 
* 
* @param inTargetDiv The DIV object that all messages are written to. 
*/ 
this.setTargetDiv = function(inTargetDiv) { 

this.targetDiv = inTargetDiv; 
this.targetDiv.innerHTML = ""; 

} // End setTargetDiv(). 

/** 
* This function is called to determine if a particular message meets or 
* exceeds the current level of the log instance and should therefore be 
* logged.（此函数用来判定现有的错误级别是否应该被显示） 
* 
* @param inLevel The level of the message being checked. 
*/ 
this.shouldBeLogged = function(inLevel) { 

if (inLevel >= this.logLevel) { 
return true; 
} else { 
return false; 
} 

} // End shouldBeLogged(). 

/** 
* This function logs messages at TRACE level. 
*（格式化显示 TRACE 的错误级别信息，往依此类推） 
* @param inMessage The message to log. 
*/ 
this.trace = function(inMessage) { 

if (this.shouldBeLogged(this.LEVEL_TRACE) && this.targetDiv) { 
this.targetDiv.innerHTML += 
"" + 
"[TRACE] " + inMessage + "
"; 
} 

} // End trace(). 

/** 
* This function logs messages at DEBUG level. 
* 
* @param inMessage The message to log. 
*/ 
this.debug = function(inMessage) { 

if (this.shouldBeLogged(this.LEVEL_DEBUG) && this.targetDiv) { 
this.targetDiv.innerHTML += 
"" + 
"[DEBUG] " + inMessage + "
"; 
} 

} // End debug(). 

/** 
* This function logs messages at INFO level. 
* 
* @param inMessage The message to log. 
*/ 
this.info = function(inMessage) { 

if (this.shouldBeLogged(this.LEVEL_INFO) && this.targetDiv) { 
this.targetDiv.innerHTML += 
"" + 
"[INFO] " + inMessage + "
"; 
} 

} // End info(). 

/** 
* This function logs messages at WARN level. 
* 
* @param inMessage The message to log. 
*/ 
this.warn = function(inMessage) { 

if (this.shouldBeLogged(this.LEVEL_WARN) && this.targetDiv) { 
this.targetDiv.innerHTML += 
"" + 
"[WARN] " + inMessage + "
"; 
} 

} // End warn(). 

/** 
* This function logs messages at ERROR level. 
* 
* @param inMessage The message to log. 
*/ 
this.error = function(inMessage) { 

if (this.shouldBeLogged(this.LEVEL_ERROR) && this.targetDiv) { 
this.targetDiv.innerHTML += 
"" + 
"[ERROR] " + inMessage + "
"; 
} 

} // End error(). 

/** 
* This function logs messages at FATAL level. 
* 
* @param inMessage The message to log. 
*/ 
this.fatal = function(inMessage) { 

if (this.shouldBeLogged(this.LEVEL_FATAL) && this.targetDiv) { 
this.targetDiv.innerHTML += 
"" + 
"[FATAL] " + inMessage + "
"; 
} 

} // End fatal(). 

} // End DivLogger(). 

源码看完后，我们来测试一下这个“小包”，来看下面的测试源码：

复制代码代码如下:

上面的测试代码里面的 <script> 段进行了 debug 的实例化，设置了显示信息的 DIV，而且设置了显示信息的最小级别为：LEVEL_DEBUG： <BR>var log = new jscript.debug.DivLogger(); <BR>log.setTargetDiv(document.getElementById("divLog")); <BR>log.setLevel(log.LEVEL_DEBUG); <BR>来看看效果如何呢： <BR><div class="htmlarea"><TEXTAREA id="runcode52315"> <script type="text/javascript">// <![CDATA[ if (typeof jscript == 'undefined') { jscript = function() { } } jscript.debug = function() { } jscript.debug.enumProps = function(inObj) { var props = ""; var i; for (i in inObj) { props += i + " = " + inObj[i] + "\n"; } alert(props); } // End enumProps(). jscript.debug.DivLogger = function() { this.LEVEL_TRACE = 1; this.LEVEL_DEBUG = 2; this.LEVEL_INFO = 3; this.LEVEL_WARN = 4; this.LEVEL_ERROR = 5; this.LEVEL_FATAL = 6; this.LEVEL_TRACE_COLOR = "a0a000"; this.LEVEL_DEBUG_COLOR = "64c864"; this.LEVEL_INFO_COLOR = "000000"; this.LEVEL_WARN_COLOR = "0000ff"; this.LEVEL_ERROR_COLOR = "ff8c00"; this.LEVEL_FATAL_COLOR = "ff0000"; this.logLevel = 3; this.targetDiv = null; this.setLevel = function(inLevel) { this.logLevel = inLevel; } // End setLevel(). this.setTargetDiv = function(inTargetDiv) { this.targetDiv = inTargetDiv; this.targetDiv.innerHTML = ""; } // End setTargetDiv(). this.shouldBeLogged = function(inLevel) { if (inLevel >= this.logLevel) { return true; } else { return false; } } // End shouldBeLogged(). this.trace = function(inMessage) { if (this.shouldBeLogged(this.LEVEL_TRACE) && this.targetDiv) { this.targetDiv.innerHTML += "<div style='color:#" + this.LEVEL_TRACE_COLOR + ";'>" + "[TRACE] " + inMessage + ""; } } // End trace(). this.debug = function(inMessage) { if (this.shouldBeLogged(this.LEVEL_DEBUG) && this.targetDiv) { this.targetDiv.innerHTML += "<div style='color:#" + this.LEVEL_DEBUG_COLOR + ";'>" + "[DEBUG] " + inMessage + ""; } } // End debug(). this.info = function(inMessage) { if (this.shouldBeLogged(this.LEVEL_INFO) && this.targetDiv) { this.targetDiv.innerHTML += "<div style='color:#" + this.LEVEL_INFO_COLOR + ";'>" + "[INFO] " + inMessage + ""; } } // End info(). this.warn = function(inMessage) { if (this.shouldBeLogged(this.LEVEL_WARN) && this.targetDiv) { this.targetDiv.innerHTML += "<div style='color:#" + this.LEVEL_WARN_COLOR + ";'>" + "[WARN] " + inMessage + ""; } } // End warn(). this.error = function(inMessage) { if (this.shouldBeLogged(this.LEVEL_ERROR) && this.targetDiv) { this.targetDiv.innerHTML += "<div style='color:#" + this.LEVEL_ERROR_COLOR + ";'>" + "[ERROR] " + inMessage + ""; } } // End error(). this.fatal = function(inMessage) { if (this.shouldBeLogged(this.LEVEL_FATAL) && this.targetDiv) { this.targetDiv.innerHTML += "<div style='color:#" + this.LEVEL_FATAL_COLOR + ";'>" + "[FATAL] " + inMessage + ""; } } // End fatal(). } // End DivLogger(). // ]]></script>

enumProps()-Shows all the properties of this link(显示此链接标签对象的所有属性和值)

Log message will appear here

DivLogger.log.trace() - Try to add a TRACE message to the above DIV (won't work because it's below the specified DEBUG level); DivLogger.log.debug() - Try to add a DEBUG message to the above DIV DivLogger.log.info() - Add a INFO message to the above DIV DivLogger.log.warn() - Add a WARN message to the above DIV DivLogger.log.error() - Add a ERROR message to the above DIV DivLogger.log.fatal() - Add a FATAL message to the above DIV

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]
在点击“enumProps()-Shows all ……”（第一个 link ）的时候浏览器弹出的框如下图所示（Opera），详细地列出了你所点击的 a 标签对象的所有属性及值：