Using is_404 to check if the current page is a 404 error page in WordPress

The WordPress is_404 function is a built-in function that checks whether the current page is a 404 error page or not. It returns a boolean value, true if the page is a 404 error page, and false if it is not.

This function can be useful for theme and plugin developers who want to customize the behavior or appearance of their website based on whether the current page is a 404 error page or not. For example, they can use this function to display a custom message or redirect the user to a different page when a 404 error occurs.

WordPress is_404 Function Parameters and Return Value

The is_404 function in WordPress does not require any parameters to be passed to it. It simply checks whether the current query is a 404 error or not.

When the is_404 function is called, it returns a boolean value indicating whether the current query is a 404 error. If the value is true, it means that the query is indeed a 404 error. If the value is false, it means that the query is not a 404 error.

Examples

How to check if the current page is a 404 error page

Use the is_404 function to check if the current page is a 404 error page.

if ( is_404() ) {
 // Do something if the current page is a 404 error page
 echo "This is a 404 error page";
} else {
 // Do something else if the current page is not a 404 error page
 echo "This is not a 404 error page";
}

How to redirect 404 error pages to a custom page

Use the is_404 function to redirect 404 error pages to a custom page.

if ( is_404() ) {
 // Redirect to a custom page
 wp_redirect( home_url( '/custom-404-page' ) );
 exit;
}

How to display a custom message on 404 error pages

Use the is_404 function to display a custom message on 404 error pages.

if ( is_404() ) {
 // Display a custom message on 404 error pages
 echo "Oops! The page you are looking for does not exist.";
}

Conclusion

In conclusion, the is_404 function is a valuable tool for developers working with web applications. By using this function, they can easily check if a particular URL or resource exists on the server, and handle the appropriate response accordingly. This can help improve the user experience by providing accurate feedback and preventing broken links. Additionally, the is_404 function can be seamlessly integrated into existing codebases and frameworks, making it a versatile solution for a wide range of web development projects. Overall, the is_404 function is a useful and efficient way to manage 404 errors and enhance the reliability of web applications.