Error handling is the process of detecting, managing, and resolving errors that occur when a website or web application runs. Maybe someone types a web address wrong, a page takes forever to load, or the website can't connect to its brain (the database). Good error handling makes sure these things don't ruin the whole experience for the person using the site.

Instead of showing technical messages, a well-designed website will use clear, helpful messages, automatically send you to a working page, or have backup plans in place.

How error handling works

Web programmers employ a handful of standard tricks for error handling.

• Client-side validation. Before you even click "submit" on a form, the website can check if you've entered things correctly, like a valid email address. These catch errors before they even start.
• Server-side error logging. The website keeps a record of any internal problems, like database failures or if an error occurred during code execution with another service it uses. This helps developers figure out what's going on and address the website's own errors. If the system is unable to recover on its own, it might throw errors, which can be caught by a catch block in the code.
• Custom error pages. Rather than displaying a generic and confusing "404 Not Found" or "500 Internal Server Error" page, sites produce detailed error messages that are more useful and on-brand.
• Graceful degradation. If one small component of a site breaks, the rest of the site should ideally continue to work.
• Automated error reporting. If there are severe problems, the system can report it automatically to the website developers to correct it promptly.

Error handling in action

You've probably seen good error handling middleware without even realizing it. Here are a few examples:

• Google’s search suggestions. When you misspell something in the search bar, Google often suggests the correct spelling instead of just saying "no results."
• Custom 404 pages. Have you ever landed on a website with a funny or helpful 404 page, like on GitHub or Airbnb? They often provide links back to the homepage or other useful sections, so you're not just stuck on a dead end.
• E-commerce checkout forms. When you're filling out an online order, many stores will highlight if you've entered your credit card number or other details incorrectly as you type, so you can fix it before you try to pay.

How to test error handling on your website

Not sure if your site handles runtime errors effectively? Try these steps.

1. Test invalid inputs. Type in the wrong kind of information in a form field and see if the err error message clearly tells you what's wrong.
2. Break the URL. Change a letter or number in a website's address and see if the "404 page" is helpful or just confusing.
3. Check slow-loading pages. If a page is loading slowly, does the site show a message like "Loading..." or does it just leave you staring at a blank screen?
4. Use browser developer tools. If you open your browser's developer tools (usually by pressing F12), you can look at the "Console" tab to see if any exception occurred that might be affecting how the site works. You might find an error object displayed here.

FAQs about error handling

Why is error handling important in web development?

It's crucial for keeping your website reliable, making sure people have a good experience, and ensuring everything runs smoothly. Without it, visitors might get frustrated and leave.

How is error handling different from debugging?

Not exactly. Error handling is about how the website reacts when something goes wrong. Debugging is the process of finding and fixing the underlying problems that cause those errors.

What are the key components of effective error handling?

A well-handled error should clearly tell the user what happened, suggest what they can do next, and avoid showing them any confusing technical details.

How do custom error pages improve user experience?

They help keep people on your site even if they land on a broken link. A good 404 page can guide them back to where they want to go instead of making them leave.

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