Get Current SharePoint Site Url using javascript
<script> var clientContext; var website; function GetSiteUrl() { clientContext = SP.ClientContext.get_current(); website = clientContext.get_web(); clientContext.load(website); clientContext.executeQueryAsync(onRequestSucceeded, onRequestFailed); } function onRequestSucceeded() { alert(website.get_url()); } function onRequestFailed(sender, args) { alert('Error: ' + args.get_message()); } </script> <a href='javascript:GetSiteUrl();'>Get URL</a>