JavaScript is a programming language commonly used to add interactivity and dynamic content to websites. Many modern websites rely on JavaScript frameworks and libraries to enhance user experience and functionality. However, JavaScript can also pose challenges for search engine crawlers like Googlebot, which may not execute JavaScript or render webpages accurately. This can result in indexing issues for content that relies heavily on JavaScript for rendering or navigation. To ensure proper indexing of JavaScript-rendered content, webmasters should follow best practices such as using progressive enhancement, providing fallback content for non-JavaScript users, and testing website rendering in Google's Fetch as Google tool or Search Console's Mobile-Friendly Test. They can also use server-side rendering or prerendering techniques to generate HTML snapshots of JavaScript-rendered content for search engine crawlers.