Introduction to try catch usage in javascript

Example code:

<script language="Javascript"> 
try
{ 
throw new Error(10,"asdasdasd") 
} 
catch (e) 
{ 
alert(e.message); 
alert(e.description) 
alert(e.number) 
alert(e.name) 
throw new Error(10,"asdasdasd") 
} 
  
</script>

You can use try...catch in Javascript for exception handling. For example:

try {
 foo.bar();
} catch (e) {
 alert(e.name + ": " + e.message);
}

Currently, the system exceptions we may get mainly include the following six types:

EvalError: raised when an error occurs executing code in eval() 
RangeError: raised when a numeric variable or parameter is outside of its valid range 
ReferenceError: raised when de-referencing an invalid reference 
SyntaxError: raised when a syntax error occurs while parsing code in eval() 
TypeError: raised when a variable or parameter is not a valid type 
URIError: raised when encodeURI() or decodeURI() are passed invalid parameters

The above six exception objects all inherit from the Error object. They all support the following two construction methods:

new Error();
new Error("异常信息");

The method of manually throwing exceptions is as follows:

try {
 throw new Error("Whoops!");
} catch (e) {
 alert(e.name + ": " + e.message);
}

If you want to determine the type of exception information, you can judge it in catch:

try {
 foo.bar();
} catch (e) {
 if (e instanceof EvalError) {
   alert(e.name + ":" + e.message);
 } 
 else if (e instanceof RangeError) {
   alert(e.name + ": " + e.message);
 } 
 // etc 
}

Error has the following main attributes:
description: Error description (only available in IE).
fileName: The file name of the error (only available in Mozilla).
lineNumber: The number of lines in error (only available in Mozilla).
message: Error message (same as description under IE)
name: Error type.
number: Error code (only available in IE).
stack: Error stack information like Stack Trace in Java (only available for Mozilla).
So in order to better understand the error message, we can change the catch part to the following form:

try {
 foo.bar();
} catch (e) {
 if (browserType != BROWSER_IE) {                
   alert("name: " + e.name + 
   "message: " + e.message + 
   "lineNumber: " + e.lineNumber + 
   "fileName: " + e.fileName + 
   "stack: " + e.stack);      
 } 
 else {            
   alert("name: " + e.name +    
   "errorNumber: " + (e.number & 0xFFFF ) + 
   "message: " + e.message");      
 } 
}

The throw command in Javascript can actually throw any object, and we can receive this object in catch. For example:

try {
 throw new Date(); // 抛出当前时间对象 
} catch (e) {
 alert(e.toLocaleString()); // 使用本地格式显示当前时间 
}

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