function sel() {
document.getElementById('testid').focus();
document.getElementById('testid').setSelectionRange(10, 10);
}
<input style="width:50px" id="testid" value="abcdefghijklmnopqrst">
<button onclick="sel()">select 10,10</button>
输入setSelectionRange(10,10)第一次不将值滚动到插入符号位置.