<button onclick="javascript:refresh();">Refresh</button>
<script>
    function refresh(){
        window.location.reload();
    }
</script>

<button onclick="window.location.reload()">Refresh</button>

<button onclick="javascript:refresh();">Refresh</button>
<script>
    function refresh(){
        window.location.href = window.location.href;
    }
</script>

<button onclick="window.location.href=window.location.href">Refresh</button>

<button onclick="javascript:refresh();">Refresh</button>
<script>
    function refresh(){
        window.history.go(0);
    }
</script>

<button onclick="window.history.go(0)">Refresh</button>