JavaScript errors in Single Page Applications can significantly disrupt user experience by causing functionalities, such as product searches or contact lists, to malfunction, often resulting in frustration due to the difficulty in diagnosing these issues. Real User Monitoring solutions, like Dynatrace, are essential tools that provide visibility into these errors by capturing user interactions and offering comprehensive insights into error occurrences across different environments. This capability allows developers to prioritize and address issues more effectively by narrowing down the error's environment and making JavaScript stack traces human-readable through the use of source maps. By employing these methods, developers can proactively reduce JavaScript errors, thus enhancing web application performance and user satisfaction, while freeing up time to focus on developing new features.