How to use Javascript to change link

Question

I want to change the url link from http://example.appspot.com/_edit/123 to http://example.appspot.com/123

How do I do this with JS?

<a id = "edit" href="_edit">edit </a>  
    <script>
        var e = document.getElementById("edit");
        var url = document.URL;

        //if edit inside the url
        if (url.indexOf("_edit")> -1){
            e.innerHTML="View Page";



        }
    </script>