Detailed explanation of try catch instances in javascript

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Summary of try catch application 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 6 types:

1. ##EvalError : raised when an error occurs executing code in eval()

2. RangeError: raised when a numeric variable or parameter is outside of its valid range

3. ReferenceError: raised when de-referencing an invalid reference

4. SyntaxError: raised when a syntax error occurs while parsing code in eval()

5. TypeError: raised when a variable or parameter is not a valid type

6. 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 do 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: Error file name (only available in Mozilla).
lineNumber: The number of lines with errors (only available in Mozilla).
message: Error message (same description under IE)
name: Error type.
number: Error code (only available in IE).
stack: Like Stack in Java Trace the same error stack information (only available to Mozilla).

7. 
   

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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