试着使用这段代码。

$('selectorOnTheInputTextBox').keypress(function (e) {
        var charCode = e.target.value.charCodeAt(e.target.value.length - 1)
        var capsOn = 
            e.keyCode && 
            !e.shiftKey &&
            !e.ctrlKey &&
            charCode >= 65 && 
            charCode <= 90;

            if (capsOn) 
               //action if true
            else
               //action if false
});

祝你好运!

当您键入时，如果caplock是打开的，它可以自动将当前字符转换为小写字母。这样，即使打开了caplocks，它的行为也不会像在当前页面上那样。为了通知您的用户，您可以显示一个文本，说明caplocks已打开，但表单条目已转换。

最近在hashcode.com上有一个类似的问题，我创建了一个jQuery插件来处理它。它还支持对数字的大写锁定识别。(在标准德语键盘布局上，大写锁定对数字有影响)。

你可以在这里查看最新版本:jquery.capsChecker

如何使用getModifierState()

如果指定了修饰符，getModifierState()方法返回true 按键被按下或激活。

你可以这样使用它:

function checkIfCapsLockIsOn(event) {
  var capsLockIsOn = event.getModifierState("CapsLock");
  console.log("Caps Lock activated: " + capsLockIsOn);
}

这将简单地检查CapsLock是ON还是OFF，并在控制台显示它。你可以改变函数的工作方式。

然后在keydown或keyup上使用这个函数。

<input type="text" onkeydown="checkIfCapsLockIsOn(event)">

We use getModifierState to check for caps lock, it's only a member of a mouse or keyboard event so we cannot use an onfocus. The most common two ways that the password field will gain focus is with a click in or a tab. We use onclick to check for a mouse click within the input, and we use onkeyup to detect a tab from the previous input field. If the password field is the only field on the page and is auto-focused then the event will not happen until the first key is released, which is ok but not ideal, you really want caps lock tool tips to display once the password field gains focus, but for most cases this solution works like a charm.

HTML

<input type="password" id="password" onclick="checkCapsLock(event)" onkeyup="checkCapsLock(event)" />

JS

function checkCapsLock(e) {
  if (e.getModifierState("CapsLock")) {
    console.log("Caps");
  }
}

https://codepen.io/anon/pen/KxJwjq

反应

onKeyPress(event) { 
        let self = this;
        self.setState({
            capsLock: isCapsLockOn(self, event)
        });
    }

    onKeyUp(event) { 
        let self = this;
        let key = event.key;
        if( key === 'Shift') {
            self.shift = false;
        }
    }

    <div>
     <input name={this.props.name} onKeyDown={(e)=>this.onKeyPress(e)} onKeyUp={(e)=>this.onKeyUp(e)} onChange={this.props.onChange}/>
                {this.capsLockAlert()}
</div>

function isCapsLockOn(component, event) {
        let key = event.key;
        let keyCode = event.keyCode;

        component.lastKeyPressed = key;

        if( key === 'Shift') {
            component.shift = true;
        } 

        if (key === 'CapsLock') {
            let newCapsLockState = !component.state.capsLock;
            component.caps = newCapsLockState;
            return newCapsLockState;
        } else {
            if ((component.lastKeyPressed !== 'Shift' && (key === key.toUpperCase() && (keyCode >= 65 && keyCode <= 90)) && !component.shift) || component.caps ) {
                component.caps = true;
                return true;
            } else {
                component.caps = false;
                return false;
            }
        }
    }