JS implement code that focuses the cursor at the end of the text

The code copy is as follows:

<span style="font-family:Times New Roman;font-size:18px;"><script type="text/javascript">

// Focus the cursor at the end of the text

function cursorEnd(){

var e = event.srcElement;

var r = e.createTextRange();

r.moveStart('character',e.value.length);

r.collapse(true);

r.select();

}

</script>

<input type=text name="test" value="test" onfocus="cursorEnd()"></span>