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Here is how you can create custom errors with completely identical to native Error's behaviour. This technique works only in Chrome and node.js for now. I also wouldn't recommend to use it if you don't understand what it does.
Error.createCustromConstructor = (function() {
function define(obj, prop, value) {
Object.defineProperty(obj, prop, {
value: value,
configurable: true,
enumerable: false,
writable: true
});
}
return function(name, init, proto) {
var CustomError;
proto = proto || {};
function build(message) {
var self = this instanceof CustomError
? this
: Object.create(CustomError.prototype);
Error.apply(self, arguments);
Error.captureStackTrace(self, CustomError);
if (message != undefined) {
define(self, 'message', String(message));
}
define(self, 'arguments', undefined);
define(self, 'type', undefined);
if (typeof init == 'function') {
init.apply(self, arguments);
}
return self;
}
eval('CustomError = function ' + name + '() {' +
'return build.apply(this, arguments); }');
CustomError.prototype = Object.create(Error.prototype);
define(CustomError.prototype, 'constructor', CustomError);
for (var key in proto) {
define(CustomError.prototype, key, proto[key]);
}
Object.defineProperty(CustomError.prototype, 'name', { value: name });
return CustomError;
}
})();
As a reasult we get
/**
* name The name of the constructor name
* init User-defined initialization function
* proto It's enumerable members will be added to
* prototype of created constructor
**/
Error.createCustromConstUse the throw statement.
JavaScript doesn't care what the exception type is (as Java does). JavaScript just notices, there's an exception and when you catch it, you can "look" what the exception "says".
If you have different exception types you have to throw, I'd suggest to use variables which contain the string/object of the exception i.e. message. Where you need it use "throw myException" and in the catch, compare the caught exception to myException.