我可以在JavaScript中为用户定义的异常定义自定义类型吗?如果是,我该怎么做?
当前回答
ES6
使用新的类和扩展关键字,现在更容易:
class CustomError extends Error {
constructor(message) {
super(message);
//something
}
}
其他回答
function MyError(message) {
this.message = message;
}
MyError.prototype = new Error;
这允许使用像..
try {
something();
} catch(e) {
if(e instanceof MyError)
doSomethingElse();
else if(e instanceof Error)
andNowForSomethingCompletelyDifferent();
}
从WebReference:
throw {
name: "System Error",
level: "Show Stopper",
message: "Error detected. Please contact the system administrator.",
htmlMessage: "Error detected. Please contact the <a href=\"mailto:sysadmin@acme-widgets.com\">system administrator</a>.",
toString: function(){return this.name + ": " + this.message;}
};
ES6
使用新的类和扩展关键字,现在更容易:
class CustomError extends Error {
constructor(message) {
super(message);
//something
}
}
//create error object
var error = new Object();
error.reason="some reason!";
//business function
function exception(){
try{
throw error;
}catch(err){
err.reason;
}
}
现在我们设置,添加原因或任何我们想要的属性到错误对象并检索它。通过使误差更合理。
你可以实现你自己的异常和它们的处理,例如:
// define exceptions "classes"
function NotNumberException() {}
function NotPositiveNumberException() {}
// try some code
try {
// some function/code that can throw
if (isNaN(value))
throw new NotNumberException();
else
if (value < 0)
throw new NotPositiveNumberException();
}
catch (e) {
if (e instanceof NotNumberException) {
alert("not a number");
}
else
if (e instanceof NotPositiveNumberException) {
alert("not a positive number");
}
}
还有另一种捕获类型化异常的语法,尽管这并不适用于所有浏览器(例如不是在IE中):
// define exceptions "classes"
function NotNumberException() {}
function NotPositiveNumberException() {}
// try some code
try {
// some function/code that can throw
if (isNaN(value))
throw new NotNumberException();
else
if (value < 0)
throw new NotPositiveNumberException();
}
catch (e if e instanceof NotNumberException) {
alert("not a number");
}
catch (e if e instanceof NotPositiveNumberException) {
alert("not a positive number");
}