Web applications are useful for various online services. These web applications are becoming ubiquitous in our daily lives. They are used for multiple purposes such as e-commerce, financial services, emails, healthcare services and many other captious services. But the presence of vulnerabilities in the web application may become a serious cause for the security of the web application. A web application may contain different types of vulnerabilities. Cross-site scripting is one of the type of code injection attacks. According to OWASP TOP 10 vulnerability report, Cross-site Scripting (XSS) is among top 5 vulnerabilities. So this research work aims to implement an effective solution for the prevention of cross- site scripting vulnerabilities. In this paper, we implemented a novel client-side XSS sanitizer that prevents web applications from XSS attacks. Our sanitizer is able to detect cross-site scripting vulnerabilities at the client-side. It strengthens web browser, because modern web browser do not provide any specific notification, alert or indication of security holes or vulnerabilities and their presence in the web application.