hi sunilas,
it totally depends upon the compatibility of the browser itself. In the file uploader widget, just check the see in browser option and then, you have to download some plugins to your browser for previewing the excel.
You can download the plugin from here
https://chrome.google.com/webstore/detail/xls-viewer-editor/cbibndgecbnjegkheljekcmjicebpfmg
hope it helps!