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测验题

How can you create custom error objects?

Topics
JAVASCRIPT
在GitHub上编辑

TL;DR

To create custom error objects in JavaScript, you can extend the built-in Error class. This allows you to add custom properties and methods to your error objects. Here's a quick example:

class CustomError extends Error {
constructor(message) {
super(message);
this.name = 'CustomError';
}
}
try {
throw new CustomError('This is a custom error message');
} catch (error) {
console.log(error.name); // CustomError
console.log(error.message); // This is a custom error message
}

How can you create custom error objects?

Extending the Error class

To create a custom error object, you can extend the built-in Error class. This allows you to inherit the properties and methods of the Error class while adding your own custom properties and methods.

class CustomError extends Error {
constructor(message) {
super(message);
this.name = 'CustomError';
}
}

Adding custom properties

You can add custom properties to your custom error class to provide more context about the error.

class CustomError extends Error {
constructor(message, errorCode) {
super(message);
this.name = 'CustomError';
this.errorCode = errorCode;
}
}
try {
throw new CustomError('This is a custom error message', 404);
} catch (error) {
console.log(error.name); // CustomError
console.log(error.message); // This is a custom error message
console.log(error.errorCode); // 404
}

Custom methods

You can also add custom methods to your custom error class to handle specific error-related logic.

class CustomError extends Error {
constructor(message, errorCode) {
super(message);
this.name = 'CustomError';
this.errorCode = errorCode;
}
logError() {
console.error(`${this.name} [${this.errorCode}]: ${this.message}`);
}
}
try {
throw new CustomError('This is a custom error message', 404);
} catch (error) {
error.logError(); // CustomError [404]: This is a custom error message
}

Using instanceof to check for custom errors

You can use the instanceof operator to check if an error is an instance of your custom error class.

try {
throw new CustomError('This is a custom error message', 404);
} catch (error) {
if (error instanceof CustomError) {
console.log('Caught a CustomError');
} else {
console.log('Caught a different type of error');
}
}

Further reading

在GitHub上编辑