js 定位 光标 到输入框的 指定位置

//从此处摘得
http://www.experts-exchange.com/Programming/Languages/Scripting/JavaScript/Q_21445351.html
Use this function:

function positionCursor(input, position) {
      var range = input.createTextRange();
      range.collapse(true);
      range.moveStart('character', position);
      range.select();
}

Called like so:

onfocus="positionCursor(this, this.length)"