文本框获得焦点，光标移到最后面

<script>
function setCursorPos( x ) {
var txtRange = x.createTextRange();
txtRange.moveStart( "character", x.value.length);
txtRange.moveEnd( "character", 0 );
txtRange.select();
}
</script>
<form >
<input type="text" onfocus="setCursorPos(this);" />
</form>