js判断键盘大小写是否开启

<input onkeypress="detectCapsLock()" type="password" name="password" />
<span style="display:none;">大写锁定键被按下，请注意大小写</span>

function detectCapsLock() {
    let e = window.event;
    let o = e.target || e.srcElement;
    let oTip = o.nextElementSibling;
    let keyCode = e.keyCode || e.which; // 按键的keyCode 
    // 65～90为26个大写英文字母，97～122号为26个小写英文字母
    if (keyCode >= 65 && keyCode <= 90)  {
        oTip.style.display = '';
    } else {
        oTip.style.display = 'none';
    }
}