JavaScript to the operating system's API with superuser privileges. These flaws have affected major browsers including Firefox, Internet Explorer, and Safari. Plugins, such as video players, Adobe Flash, and the wide range of ActiveX controls enabled by default in Microsoft Internet Explorer, may also have flaws exploitable via JavaScript (such flaws have been exploited in the past). In Windows Vista, Microsoft has attempted to contain the risks of bugs such as buffer overflows by running the Internet Explorer process with limited privileges. Google Chrome similarly confines its page renderers to their own "sandbox". Web browsers are capable of running JavaScript outside
Upload components for uploading files are still not part of the standard, HTML5 upload components are not common at the moment. Their support is restricted to a subset of browsers. HTML5 support has been steadily improving. The best coverage of HTML5 features is provided by the latest version of Chrome, Firefox, Safari and Opera. Internet Explorer provides the least support. Internet Explorer 10 has less support than versions of other browsers; however the coverage will be twice as good as Internet Explorer 9. iOS 5 has a sufficiently high level of HTML5 support; however, its level of support remains lower than for